Tooth and Nail is a must answer in a format full of high mana, must answer cards. I really don't find it any more unfair than, say, Insurrection or a second or third turn Felidar Sovereign from Oloro, etc.. We play stuff like Zur, Arcum, Damia, etc., here, so building up to 9 to cast it is a chore if you don't already have infinite mana.
Try hards definitely understand the difference between Bargain and Necropotence. Resolving Bargain is 39+- cards drawn, and the controller will win.
Necropotence, while allowing you to dig, at least doesn't allow you a grip of 30+ cards that any well built deck with Bargain can cast in the same turn. You at least have to go down to 7, and you don't get them until end of turn.
This is like comparing Griselbrand to Damia, Sage of Stone, as they don't serve the same purpose but one is infinitely more powerful than the other at enabling stupid numbers of combos after resolution.
There's no way yawgmoth's bargain hits the table and doesn't completely warp the game around messing with the controller: You'll gave to, or you'll lose.
How many creatures are you running? I see Sarkhan Vol in a lot of Superfriends list that run maybe 6 creatures at max, so he's basically an expensive Threaten if you don't have Doubling Season or another doubler. I don't value Threaten effects very highly in Commander ('cause, well, if it's a high value target like Blightsteel, odds are that he's coming in *and* swinging the same turn, or coming out at instant speed on someone's end step and then swinging. If you have a threaten effect just sitting on board, that typically makes you the priority #1 target, lol). I don't see value in him, so I'd drop him for new Jace, but if you run enough other creatures to warrant him being useful as more than just a bad Threaten twice, then sure thing. You need a crit mass of token producers or a doubler for Sarkhan to be good, while Jace would be good by itself most of the time.
If you can't tell, I much prefer to just deal with the creatures instead of stealing them once or twice because if it's that bad that you want it, yourself, then it should be dead.
If you're interested in keeping Sylvan Ranger, then perhaps swap Crop Rotation in over Rofellos, since the largest target for Crop Rotation is Gaea's Cradle, and in French 1v1, where Rofellos is legal, you can't play Gaea's Cradle.
Then, if you do French, just switch Rofellos back in and drop Order/Cradle/Rotation for 2 other cards since you can gain quite a bit of acceleration off of him and they're not legal alongside him, lol.
I hope I explained that right. I don't exactly have the most concise manner of speaking when it's this late, and right now it's 6AM and nearing end of shift, lol.
In order to compare the new Planeswalkers to the cards you're already running, and evaluate which may be the better choices, you'd need to post the list of Planeswalkers you're running so that people could do the comparisons.
There are way too many people who run Superfriends but pack things like Chandra, the Firebrand or something when they run 3-4 instants/sorceries at max, and like 1 of them benefits from being copied, for example (leaving the ultimate as being really the only valuable part of the card, and therefore only worthwhile if certain conditions are met). So without an idea of what you already run, there's no way to help you with evaluation at all.
So, I built my wife an Ezuri Commander deck to get her into the format and she loves it. I really don't feel like typing out the whole deck list (and it's a multiplayer deck anyway), but there are a few cards you're missing that I think you could cleanly take full advantage of:
Staff of Domination: If you control Priest of Titania, Elvish Archdruid, Wirewood Channeler, or Karametra's Acolyte with this while you have 5+ Elves/mana symbols on the battlefield, you generate infinite mana. You have a mana outlet in the Commander zone, meaning you do this and you immediately win that same turn. Staff requires 1 more Elf/mana symbol than Umbral Mantle would require, but has the added functionality of allowing you to gain as much life as you want and draw your library in response to removal, Fog, or combat skipping effect (Stonehorn Dignitary and the like), which can potentially give you the out to remove a permanent causing you problems that you otherwise couldn't just attack through. Honestly, I think it would be a better use of a slot than Masked Admirers, whom I've always found to be too slow to actually do anything useful.
Why Civic Wayfinder? Yavimaya Dryad pulls Forests out of the library, which is the only card Wayfinder could pull, too, but it at least puts it directly onto the battlefield. Unless I'm missing something amazing, I don't see much purpose in tutoring basic lands to your hand. On that note, I'd drop something for Crop Rotation, probably Sylvan Ranger, as it didn't make the cut in my wife's deck but Rotation did.
Natural Order is a great little sorcery you're missing (which, if you're proxying Cradle, why not this too). You can use it to swap a mana dork for a Craterhoof, allowing you an Overrun effect on command. I'd actually suggest cutting Overrun for Natural Order for this reason alone.
So is this a French 1v1 deck? 'Cause Cradle is banned in French, but Rofellos is banned in the multiplayer ban list. Swap Rofellos for Sol Ring or something if multiplayer ban list, drop Cradle if French. Right now I don't think this adheres to either ban list, lol, but if you're 1v1 using the multiplayer ban list, Cradle, Natural Order, and Sol Ring are all okay to run.
Is it wrong that I haven't been hugely favoring "Return to" blocks since roughly Scars of Mirrodin? After having played the original Ravnica block, I thought RtR's block was eh (GTC and DGM were pretty meh to me), and then I've hated absolutely everything about Zendikar 2: Electric Boogaloo, except this time they messed up Modern while they were at it (actually kind of think the Eldrazi deck is just as bad as Mental Misstep, an abject mistake lol).
Then again, I've mostly just been playing Legacy, Modern, Commander, and prereleases.... So... maybe I just missed out on the best those blocks could offer, but I'm so damn tired of Return To blocks. So, I'm sincerely hoping that Return to Return to Ravnica: Get Your Guildpacts Here is not a block we're seeing in the next few years.
I think a lot of people have misinterpreted my dilemma. It's not about the cost of keeping up with buying new foils for the deck, or about the value of the cards I have. It's about the fact that, because this deck of foil cards is basically "my baby," I have a hard time making changes to it in order to try new things when I don't have a foil copy of new cards on hand. It's inhibiting my ability and desire to try new things, to push the deck in a radically different direction if I feel it's gotten stale. The question is simply whether or not to dismantle the deck, not to sell the cards, in order to breathe new life into it, or to leave it intact as a testament to years of tinkering and playing, a question which is made harder by the fact that I *like* seeing it the way it is.
Do you want to radically push your deck in a different direction? That's an important question to answer. How many decks do you have? Is Omnath the only one you're going to go through this sort of thing with? Is there a particular problem with testing out a new addition as a nonfoil (I honestly see no issue in that. I would honestly check if Nissa, Voice of Zendikar is any good in Omnath before spending almost 3x the cost of a nonfoil to test one out)? If it's really that big of an issue, why not buy a nonfoil copy, then make your own foil proxy until you have the cash to get the foil? I do have a guy in this area who does this sort of thing (foils out a deck but has a restricted budget), but he tests with proxies to ensure his purchase is the correct one, and then runs a proxy foil until the foil's price drops due to lowered Standard play or rotation. Overall, de-foiling a deck is probably more stressful than just leaving the thing together and making small changes over time.
I've never had the want to do so with any of my nine Commander decks in the last three years if they actually work as they're supposed to. I basically built 1-2 decks of each archetype and ran with it (Chainer and Roon are my control decks, Ghave, Nekusar, and Arcum are my combo decks, Ezuri and Sliver Overlord are my aggro decks, Kemba and Uril are my Voltron decks), and unless there was an issue with actually winning, I have yet to feel the need to drop 10-20 cards out of any of them to drive them in a different direction. I'm currently building Zur, which is looking to be a no-nonsense Doomsday/Ad Nauseam deck with him to grab Necropotence if I run out of gas (so I'll have 2 high tier Commander options, and the rest I can use to gauge a playgroup's level). I have the exact opposite issue: I build a deck and, if it works well, I never take it apart, only updating it occasionally. I then get to work on the next deck which is probably why I have thirty different 60 card decks (mostly casual, 4 Legacy decks (Reanimator, Painter, Enchantress, Elves), 4 Modern decks (2, now, with the latest ban wave), etc.), and 9 Commander decks with a 10th in the works.
As a result, I interpret your 'dilemma' okay, but I see nothing wrong with it. I don't update that often or radically change my decks for change's sake, so I still see absolutely no reason to de-foil your deck unless you absolutely have to do so (you need the money for something else, for example). The issue you're running into doesn't sound insurmountable in the slightest as you do still have options. If it's really that big of an issue, though, and you're wanting to change something like 40 cards in Omnath, then just shove your foils off to the side and add in all of the nonfoil, different cards- I still don't recommend selling the foils unless you absolutely need the cash.
If you've already foiled it, then I just recommend not bothering. You obviously and clearly like it, so unless someone is willing to trade you, say, 3 Gaea's Cradle for your judge foil, I see no benefit in the added stress you would bring upon yourself to find the best deal with each sale or exchange. Similarly, I find that a lot of times, new cards I'm extremely interested in testing out are actually not all that beneficial to my decks, overall. I may have added over 10-12 cards to my Ghave deck in the last year, but only 2 of them stuck: Evolutionary Leap and Zulaport Cutthroat. My Arcum deck has received, I think, two cards total in the last year, one being Hangarback Walker and the other, Hedron Crawler (actually, I'm still using a proxy for Hangarback and everyone in my group knows it. I'm not spending $10 on a better Myr Sire since much of the time they're the same card in the first 3 turns).
So, maybe just don't run out and grab the next big thing immediately? I tend to wait until Standard players get their fill, then I'll grab what I wanted. I usually do this unless it's some kind of super amazing card that leads me to think it will revolutionize one of my 9 Commander decks, but I haven't come across one of those in a long ass time. In cases of cards where the foil is 5x the price of the nonfoil, people I play with will buy the nonfoil and run it until the foil price drops, usually a couple months down the road (rarely, if ever, does it take the full Standard cycle). One guy, who is impatient, will buy a copy of the card and then print his own foil proxy and use that in his deck until the *real* foil price drops on the second market. I guess that's another option.
For what it's worth, though, I strongly dislike foil cards a lot. I live in an extremely humid area and I absolutely cannot tolerate the foil bend (even double sleeved with perfect fits and Dragon Shields, the cards will bend without enough time. Living in a valley apparently just does that to foils). So, it should say something if even someone like me is telling you to, "Just keep the deck together as it is." I mean, I traded 1 foil Mox Opal from Scars for 2 nonfoils because I hate foil bending so much. I'd do it with my Rise of the Eldrazi foil Emrakul, the Aeons Torn and foil Cavern of Souls in a heartbeat, because I hate being able to detect where the cards are in my deck, while players at the Pburg card shop have so many foil cards their whole decks curl in the middle and you can clearly see where the nonfoils are, ugh.
Not a fan of Jace Beleren: If you have room for him, you have room for Intruder Alarm, and I can't think of any case in which you'd want him over Alarm (Alarm + Overlord = tutor out Gemhide Sliver, then after untapping, tutor out Heart Sliver. If you have at least 4 Slivers by this point, you may now begin tutoring out and casting every single Sliver in your library starting from CMC1 and up and then win by swinging them, sacrificing them, tapping them for Psionic Sliver, etc.). 1 card per turn is fairly meh, and if you have that many open slots in Sliver Overlord that you'd consider Beleren, then you have to consider him against Descendant's Path, Intruder Alarm, Wargate (which would most likely be used to get Mana Echoes, Intruder Alarm, etc.) or Bring to Light, etc.. In fact, any tutor is something I would run over him simply because they would be better in combination with Overlord (Green Sun's Zenith and Chord of Calling, for example, tutor out Seedborn Muse. Muse is important because it allows you to untap and tutor out, then cast, Quick Sliver. Congratulations, you now have a better combined board than if you had cast Prophet of Kruphix pre-ban, as you can spend 3+any Slivers casting cost to drop any Sliver from your library. I find this important because of Crystalline Sliver, Sliver Hivelord, Hibernation Sliver, Pulmonic Sliver, Sedge Sliver, Crypt Sliver, Diffusion Sliver, and tons more).
So yeah, marginal card advantage Planeswalkers are not ones I like in Overlord. The deck is inherently weak (since it focuses so much on creatures, and its combos are fairly easy to stop) and therefore needs bigger impact spells. Only Domri Rade and Ugin, the Spirit Dragon seem to have the benefits that actually significantly change a board state in your favor should you meet the proper criteria, and Ugin would probably just be better as a copy of All is Dust. Domri is another that, while his ultimate seems useful, a Sliver Overlord deck that's properly build will have shroud, double strike, trample, and haste, long before turn 7, making his ability redundant (notwithstanding his +1 isn't even guaranteed value).
.... So yeah, I don't think you actually need any Planeswalkers. I could see you running Ugin, the Spirit Dragon and Ghostflame Sliver or Domri, though. Other Planeswalkers with abilities that normally help aggro (like Venser, the Sojourner's -1) are pretty irrelevant in Slivers because you have things like Shifting Sliver and tons of different cards to provide varying forms of evasion, not to mention one of the easiest to protect board states in aggro decks since you can shroud, indestructible and even bring Slivers back to hand for only 2 life and re-cast them with removal on the stack. This is just my $.02 as someone who's played Sliver Overlord for the last year or so in a combo infested meta, though.
Those cards read... "Are you playing blue?, if not you lose", tooth 'n nail still needs creatures to win, those can be interacted with by other colours.
You'd force every deck to run warping wail.
Turbo ramping isn't even difficult.
There are plenty of non blue answers to Biorhythm.
If that were the case, and the RC wanted to make sure that everyone held their mana open at all times for someone to cast a Biorhythm, then Coalition Victory would be the card to come off the ban list first, I think.
All decks have access to Wasteland, Strip Mine, etc., and a Slaughter Pact or Rout on the Commander (or Transguild Courier, if that'd ever be a thing lol) stops the win attempt without forcing the game into a draw out of nowhere- which is what would happen if you remove the Biorhythm caster's creature. Coalition Victory also has less attempt for abuse by bad or douchey players. Game going poorly or one player is vindictive as all hell and know he won't win? May as well steal the win from someone else by forcing a tie, specifically through EoT Evacuation and Biorhythm on main phase. If someone has a creature with flash, whatever, these things happen. Those kind of dick-headed players are quite literally everywhere from what I hear (if things got so bad with Sylvan Primordial and Prophet of Kruphix that they needed the axe, then logic follows that people don't have fun responsibly and apparently at the expense of someone else).
So.... I think Coalition Victory should come off before Biorhythm, using your criteria. That's all.
Pretty sure neither should come off the ban list, either, because competitive Commander doesn't want them (I can't see Damia or Animar really playing it over anything in their 99, let alone Zur, Arcum, Brago etc., wouldn't care about it as a second turn Land Equilibrium, Stasis, Winter Orb, etc., would basically stop it from ever occurring before they're beaten), but casual Commander would be overflowing with rivers of salt due to them. I really see no benefit for either group, honestly.
I ran it in Roon of the Hidden Realm and Sliver Overlord. Overlord is getting Seedborn Muse, which basically does the exact same thing in that deck (untap, tutor and cast Quick Sliver? Thank you!), so an already weak deck did not get weaker.
Roon is going to miss Prophet a little bit, but I already ran Seedborn and Teferi, so I'm probably shoving Defense of the Heart in its slot and Forbidden Orchard over one of my other lands. Problem solved, as far as that deck goes (we play big multiplayer games, so its rare there's no one with 3 creatures. There's a Ghave, Krenko, Animar, Kemba, and Ezuri deck around here, so, you know. I don't fear not being able to trigger Defense of the Heart).
For Nekusar, the Mindrazer and Sigil of Sleep, you'd be correct. Nekusar is dealing 1 damage seven times, meaning Sigil will trigger seven times unless something else stops it.
For Mind over Matter, I'm not exactly sure what the question is, here? Mind Over Matter is an enchantment with an activated ability: To untap two permanents, you would need to discard two cards. So, for example, if you have Temple Bell in play as well, you can tap the Bell, draw a card, discard the card to Mind Over Matter to untap the Bell, draw a card again, discard that card to again untap the Bell, etc.. You must discard 1 card each time you activate Mind Over Matter. It has an activated ability with an activation cost of discard 1 card: Do a thing. You can't just discard a card and then untap something forever. Also, there's nothing saying you *can't* activate it more than once, so as long as you have cards to discard, you can untap or tap a permanent using it.
For your last issue, your opponent was somewhat correct. Tapping lands for mana does not use the stack, and cannot be responded to. You never received priority to say, "In response" in the scenario you mentioned. If you want to prevent him from casting a creature, you can tap his lands on his upkeep (remember: Untap step, upkeep, draw, *then* pre-combat main phase, which is when he could cast a creature without flash). If his creature has flash you cannot stop him from casting it using Mind Over Matter. Also, he can tap his lands for mana, responding to Mind Over Matter's activations, and cast a creature anyway should you decide to do it during his main phase (once the stack is empty). Once the land is tapped for mana, it is too late to tap it with a spell or ability (the same also goes for attackers: If you let him get to the declare attackers step to find out what he's attacking with, the creature will already be tapped and you can't stop it from attacking you with Mind Over Matter by that point).
Nothing is really off limits at our tables, but we basically have an understanding that whoever has the most aggressive deck at the time is going to have to fight through some stuff.
In one game, we'll have Oloro drop a Felidar Sovereign on the third turn (with him on the play) after casting something, anything, to gain life prior. The player with a Bant Charm in hand was taken aback that he didn't have WUG on his third turn (instead having Temple Garden, Sunpetal Grove and a Plains, which was otherwise acceptable since he had Skyshroud Claim in hand, but not when you need those colors t3). In a different game, a player cast second turn Land Equilibrium off of a Mana Crypt and first turn Talisman of Progress- locking everyone at two mana per turn for the rest of the game. We had one player sitting there with a Krosan Grip in hand that he couldn't cast because he didn't reach a third mana source for the rest of the game, and not for lack of trying (you ever see a Llawnowar Elves be a must counter? lol)
For some decks, there's hardly a different between the above games, and in both cases, depending upon your deck's composition, you get to know, "Oh, I lost before my fourth turn." I don't view either of the above any different from someone saying, "I assembled Mazirek, Blasting Station, and Kitchen Finks on turn 4, I win because everyone is tapped out." These things happen.
And yeah, you shuffle up and play another game. It's Magic- that's what's fun about it is that you can use diverse ranges of strategies in order to win. Is that really any worse than t2 Land Equilibrium or turn 3 Laboratory Maniac after a Doomsday?
I don't make agreements with players in my playgroup without having some sort of, "All hell breaks loose" in the event of them going back on it.
For example, some time ago we had a player who was about to be killed by a Xenagos, God of Revels player by being dealt some 32 damage in one turn. I informed the player who was about to be killed that I would stop it for him in exchange for him to stop messing with me for the next couple of turns (he had spent his prior two-three turns countering all of my spells for practically no reason, which is why he wound up in position to be killed by the other player). I flickered the attacker from Xenagos, the other player survived, and then on his turn tried to exile multiple pieces of my board state.
I responded with a Ghostway, flashing in Deadeye Navigator, and then proceeded to use Brutalizer Exarch and all of my remaining mana to tuck all but one of his lands. I was extending the game for his benefit, not for mine, so I used what I had at my disposal and then railroaded him to victory.
I stopped asking for assistance a long time ago in multiplayer games. My, "Requests" are now more in the neighborhood of, "If someone doesn't do something about X, I'm nuking the board and screwing over everyone except myself."
Necropotence, while allowing you to dig, at least doesn't allow you a grip of 30+ cards that any well built deck with Bargain can cast in the same turn. You at least have to go down to 7, and you don't get them until end of turn.
This is like comparing Griselbrand to Damia, Sage of Stone, as they don't serve the same purpose but one is infinitely more powerful than the other at enabling stupid numbers of combos after resolution.
There's no way yawgmoth's bargain hits the table and doesn't completely warp the game around messing with the controller: You'll gave to, or you'll lose.
If you can't tell, I much prefer to just deal with the creatures instead of stealing them once or twice because if it's that bad that you want it, yourself, then it should be dead.
Then, if you do French, just switch Rofellos back in and drop Order/Cradle/Rotation for 2 other cards since you can gain quite a bit of acceleration off of him and they're not legal alongside him, lol.
I hope I explained that right. I don't exactly have the most concise manner of speaking when it's this late, and right now it's 6AM and nearing end of shift, lol.
There are way too many people who run Superfriends but pack things like Chandra, the Firebrand or something when they run 3-4 instants/sorceries at max, and like 1 of them benefits from being copied, for example (leaving the ultimate as being really the only valuable part of the card, and therefore only worthwhile if certain conditions are met). So without an idea of what you already run, there's no way to help you with evaluation at all.
Staff of Domination: If you control Priest of Titania, Elvish Archdruid, Wirewood Channeler, or Karametra's Acolyte with this while you have 5+ Elves/mana symbols on the battlefield, you generate infinite mana. You have a mana outlet in the Commander zone, meaning you do this and you immediately win that same turn. Staff requires 1 more Elf/mana symbol than Umbral Mantle would require, but has the added functionality of allowing you to gain as much life as you want and draw your library in response to removal, Fog, or combat skipping effect (Stonehorn Dignitary and the like), which can potentially give you the out to remove a permanent causing you problems that you otherwise couldn't just attack through. Honestly, I think it would be a better use of a slot than Masked Admirers, whom I've always found to be too slow to actually do anything useful.
Why Civic Wayfinder? Yavimaya Dryad pulls Forests out of the library, which is the only card Wayfinder could pull, too, but it at least puts it directly onto the battlefield. Unless I'm missing something amazing, I don't see much purpose in tutoring basic lands to your hand. On that note, I'd drop something for Crop Rotation, probably Sylvan Ranger, as it didn't make the cut in my wife's deck but Rotation did.
Natural Order is a great little sorcery you're missing (which, if you're proxying Cradle, why not this too). You can use it to swap a mana dork for a Craterhoof, allowing you an Overrun effect on command. I'd actually suggest cutting Overrun for Natural Order for this reason alone.
So is this a French 1v1 deck? 'Cause Cradle is banned in French, but Rofellos is banned in the multiplayer ban list. Swap Rofellos for Sol Ring or something if multiplayer ban list, drop Cradle if French. Right now I don't think this adheres to either ban list, lol, but if you're 1v1 using the multiplayer ban list, Cradle, Natural Order, and Sol Ring are all okay to run.
Then again, I've mostly just been playing Legacy, Modern, Commander, and prereleases.... So... maybe I just missed out on the best those blocks could offer, but I'm so damn tired of Return To blocks. So, I'm sincerely hoping that Return to Return to Ravnica: Get Your Guildpacts Here is not a block we're seeing in the next few years.
Do you want to radically push your deck in a different direction? That's an important question to answer. How many decks do you have? Is Omnath the only one you're going to go through this sort of thing with? Is there a particular problem with testing out a new addition as a nonfoil (I honestly see no issue in that. I would honestly check if Nissa, Voice of Zendikar is any good in Omnath before spending almost 3x the cost of a nonfoil to test one out)? If it's really that big of an issue, why not buy a nonfoil copy, then make your own foil proxy until you have the cash to get the foil? I do have a guy in this area who does this sort of thing (foils out a deck but has a restricted budget), but he tests with proxies to ensure his purchase is the correct one, and then runs a proxy foil until the foil's price drops due to lowered Standard play or rotation. Overall, de-foiling a deck is probably more stressful than just leaving the thing together and making small changes over time.
I've never had the want to do so with any of my nine Commander decks in the last three years if they actually work as they're supposed to. I basically built 1-2 decks of each archetype and ran with it (Chainer and Roon are my control decks, Ghave, Nekusar, and Arcum are my combo decks, Ezuri and Sliver Overlord are my aggro decks, Kemba and Uril are my Voltron decks), and unless there was an issue with actually winning, I have yet to feel the need to drop 10-20 cards out of any of them to drive them in a different direction. I'm currently building Zur, which is looking to be a no-nonsense Doomsday/Ad Nauseam deck with him to grab Necropotence if I run out of gas (so I'll have 2 high tier Commander options, and the rest I can use to gauge a playgroup's level). I have the exact opposite issue: I build a deck and, if it works well, I never take it apart, only updating it occasionally. I then get to work on the next deck which is probably why I have thirty different 60 card decks (mostly casual, 4 Legacy decks (Reanimator, Painter, Enchantress, Elves), 4 Modern decks (2, now, with the latest ban wave), etc.), and 9 Commander decks with a 10th in the works.
As a result, I interpret your 'dilemma' okay, but I see nothing wrong with it. I don't update that often or radically change my decks for change's sake, so I still see absolutely no reason to de-foil your deck unless you absolutely have to do so (you need the money for something else, for example). The issue you're running into doesn't sound insurmountable in the slightest as you do still have options. If it's really that big of an issue, though, and you're wanting to change something like 40 cards in Omnath, then just shove your foils off to the side and add in all of the nonfoil, different cards- I still don't recommend selling the foils unless you absolutely need the cash.
So, maybe just don't run out and grab the next big thing immediately? I tend to wait until Standard players get their fill, then I'll grab what I wanted. I usually do this unless it's some kind of super amazing card that leads me to think it will revolutionize one of my 9 Commander decks, but I haven't come across one of those in a long ass time. In cases of cards where the foil is 5x the price of the nonfoil, people I play with will buy the nonfoil and run it until the foil price drops, usually a couple months down the road (rarely, if ever, does it take the full Standard cycle). One guy, who is impatient, will buy a copy of the card and then print his own foil proxy and use that in his deck until the *real* foil price drops on the second market. I guess that's another option.
For what it's worth, though, I strongly dislike foil cards a lot. I live in an extremely humid area and I absolutely cannot tolerate the foil bend (even double sleeved with perfect fits and Dragon Shields, the cards will bend without enough time. Living in a valley apparently just does that to foils). So, it should say something if even someone like me is telling you to, "Just keep the deck together as it is." I mean, I traded 1 foil Mox Opal from Scars for 2 nonfoils because I hate foil bending so much. I'd do it with my Rise of the Eldrazi foil Emrakul, the Aeons Torn and foil Cavern of Souls in a heartbeat, because I hate being able to detect where the cards are in my deck, while players at the Pburg card shop have so many foil cards their whole decks curl in the middle and you can clearly see where the nonfoils are, ugh.
So yeah, marginal card advantage Planeswalkers are not ones I like in Overlord. The deck is inherently weak (since it focuses so much on creatures, and its combos are fairly easy to stop) and therefore needs bigger impact spells. Only Domri Rade and Ugin, the Spirit Dragon seem to have the benefits that actually significantly change a board state in your favor should you meet the proper criteria, and Ugin would probably just be better as a copy of All is Dust. Domri is another that, while his ultimate seems useful, a Sliver Overlord deck that's properly build will have shroud, double strike, trample, and haste, long before turn 7, making his ability redundant (notwithstanding his +1 isn't even guaranteed value).
.... So yeah, I don't think you actually need any Planeswalkers. I could see you running Ugin, the Spirit Dragon and Ghostflame Sliver or Domri, though. Other Planeswalkers with abilities that normally help aggro (like Venser, the Sojourner's -1) are pretty irrelevant in Slivers because you have things like Shifting Sliver and tons of different cards to provide varying forms of evasion, not to mention one of the easiest to protect board states in aggro decks since you can shroud, indestructible and even bring Slivers back to hand for only 2 life and re-cast them with removal on the stack. This is just my $.02 as someone who's played Sliver Overlord for the last year or so in a combo infested meta, though.
If that were the case, and the RC wanted to make sure that everyone held their mana open at all times for someone to cast a Biorhythm, then Coalition Victory would be the card to come off the ban list first, I think.
All decks have access to Wasteland, Strip Mine, etc., and a Slaughter Pact or Rout on the Commander (or Transguild Courier, if that'd ever be a thing lol) stops the win attempt without forcing the game into a draw out of nowhere- which is what would happen if you remove the Biorhythm caster's creature. Coalition Victory also has less attempt for abuse by bad or douchey players. Game going poorly or one player is vindictive as all hell and know he won't win? May as well steal the win from someone else by forcing a tie, specifically through EoT Evacuation and Biorhythm on main phase. If someone has a creature with flash, whatever, these things happen. Those kind of dick-headed players are quite literally everywhere from what I hear (if things got so bad with Sylvan Primordial and Prophet of Kruphix that they needed the axe, then logic follows that people don't have fun responsibly and apparently at the expense of someone else).
So.... I think Coalition Victory should come off before Biorhythm, using your criteria. That's all.
Pretty sure neither should come off the ban list, either, because competitive Commander doesn't want them (I can't see Damia or Animar really playing it over anything in their 99, let alone Zur, Arcum, Brago etc., wouldn't care about it as a second turn Land Equilibrium, Stasis, Winter Orb, etc., would basically stop it from ever occurring before they're beaten), but casual Commander would be overflowing with rivers of salt due to them. I really see no benefit for either group, honestly.
Roon is going to miss Prophet a little bit, but I already ran Seedborn and Teferi, so I'm probably shoving Defense of the Heart in its slot and Forbidden Orchard over one of my other lands. Problem solved, as far as that deck goes (we play big multiplayer games, so its rare there's no one with 3 creatures. There's a Ghave, Krenko, Animar, Kemba, and Ezuri deck around here, so, you know. I don't fear not being able to trigger Defense of the Heart).
For Mind over Matter, I'm not exactly sure what the question is, here? Mind Over Matter is an enchantment with an activated ability: To untap two permanents, you would need to discard two cards. So, for example, if you have Temple Bell in play as well, you can tap the Bell, draw a card, discard the card to Mind Over Matter to untap the Bell, draw a card again, discard that card to again untap the Bell, etc.. You must discard 1 card each time you activate Mind Over Matter. It has an activated ability with an activation cost of discard 1 card: Do a thing. You can't just discard a card and then untap something forever. Also, there's nothing saying you *can't* activate it more than once, so as long as you have cards to discard, you can untap or tap a permanent using it.
For your last issue, your opponent was somewhat correct. Tapping lands for mana does not use the stack, and cannot be responded to. You never received priority to say, "In response" in the scenario you mentioned. If you want to prevent him from casting a creature, you can tap his lands on his upkeep (remember: Untap step, upkeep, draw, *then* pre-combat main phase, which is when he could cast a creature without flash). If his creature has flash you cannot stop him from casting it using Mind Over Matter. Also, he can tap his lands for mana, responding to Mind Over Matter's activations, and cast a creature anyway should you decide to do it during his main phase (once the stack is empty). Once the land is tapped for mana, it is too late to tap it with a spell or ability (the same also goes for attackers: If you let him get to the declare attackers step to find out what he's attacking with, the creature will already be tapped and you can't stop it from attacking you with Mind Over Matter by that point).
Hope this helps.
In one game, we'll have Oloro drop a Felidar Sovereign on the third turn (with him on the play) after casting something, anything, to gain life prior. The player with a Bant Charm in hand was taken aback that he didn't have WUG on his third turn (instead having Temple Garden, Sunpetal Grove and a Plains, which was otherwise acceptable since he had Skyshroud Claim in hand, but not when you need those colors t3). In a different game, a player cast second turn Land Equilibrium off of a Mana Crypt and first turn Talisman of Progress- locking everyone at two mana per turn for the rest of the game. We had one player sitting there with a Krosan Grip in hand that he couldn't cast because he didn't reach a third mana source for the rest of the game, and not for lack of trying (you ever see a Llawnowar Elves be a must counter? lol)
For some decks, there's hardly a different between the above games, and in both cases, depending upon your deck's composition, you get to know, "Oh, I lost before my fourth turn." I don't view either of the above any different from someone saying, "I assembled Mazirek, Blasting Station, and Kitchen Finks on turn 4, I win because everyone is tapped out." These things happen.
And yeah, you shuffle up and play another game. It's Magic- that's what's fun about it is that you can use diverse ranges of strategies in order to win. Is that really any worse than t2 Land Equilibrium or turn 3 Laboratory Maniac after a Doomsday?
For example, some time ago we had a player who was about to be killed by a Xenagos, God of Revels player by being dealt some 32 damage in one turn. I informed the player who was about to be killed that I would stop it for him in exchange for him to stop messing with me for the next couple of turns (he had spent his prior two-three turns countering all of my spells for practically no reason, which is why he wound up in position to be killed by the other player). I flickered the attacker from Xenagos, the other player survived, and then on his turn tried to exile multiple pieces of my board state.
I responded with a Ghostway, flashing in Deadeye Navigator, and then proceeded to use Brutalizer Exarch and all of my remaining mana to tuck all but one of his lands. I was extending the game for his benefit, not for mine, so I used what I had at my disposal and then railroaded him to victory.
I stopped asking for assistance a long time ago in multiplayer games. My, "Requests" are now more in the neighborhood of, "If someone doesn't do something about X, I'm nuking the board and screwing over everyone except myself."