I read your series today and I really liked them. Your opinions are well supported, and your analysis covers each keyword from many different aspects in a broad view.
I have one correction to make though. Suspend wasn't the first ability to use the exile zone in a way that no other card could, imprint in Mirrodin block did it first (albeit in an unexciting and not very memorable way). This mechanic still has quite a lot of untapped design space.
I don't have an idea what the first keyword would be. Trample is one of the most beloved mechanics of all time, that plays well and has history. However, it's not very innovative - many attacking/blocking mechanic have been made alongside it from the very beginning, and it's not as resonant as flying.
OTOH I definitely know what will make the worst ten keywords of all time: Shroud!
a) He won't survive until your next turn
b) You want to counter things if needed be.
If you want to play it later, you'll need three open blue mana and still most of the time he'll counter the removal pointed at him and not the real target. 2/1 for UU is not really threatening either.
With that in mind, a card that costs triple red has to be played in red-based decks only. Red-heavy decks tend to be aggro decks anyway most of the time, and ramp decks have trouble with the mana cost and better targets to choose. So yes, it can be supported but I don't want to.
Duh, reading the cards you include in your cube is tech. I don't think it's that strong but he's best I don't play yet and will surely be more playable.
I had the space and I'm willing to try. Most green four-drops cost double green, making them unsplashable. Rhox Charger seems worthy of its cost and is splashable.
Have you had any good experience with it? If so I'll be surprised.
With your blink theme he might as well be a 4/4 for :2mana:, and with the never-dying mechanic it's some good.
I didn't really cut him, I just moved him to the blue section (I added him there in my update). I do believe I play worse artifacts than Sigil of Distinction (or at least I did before this update).
On the same note, I personally like Crystal Shard. I think Erratic Portal should be in this cube, but I didn't add him yet because Crystal Shard hadn't made very impressive appearances yet and if I add him now people won't even give it a chance.
I'll keep that in mind.
Thanks you all
If I know that they'll table though, Gifts + K.Guide is tempting.
White:
Out: Endless Horizons
In: Miraculous Recovery
Endless Horizons costs too much and is way too slow to be effective. Mono white (or a deck with large amounts of white cards) tends to be very aggressive, and four mana is just too much for them. I wish to change that a bit, however, and both of the new cards in white aren't aimed for aggro strategies.
Miraculous Recovery was discussed in the forums a lot lately, and I think it'll help white to be more open-ended.
Out: Jotun Grunt
In: Crovax, Ascendant Hero
Jotun Grunt was used occasionally as a sideboard card, but it is still too narrow. Graveyards don't fill up fast in this cube. Crovax got out of the cube during some point, and it's the time to get him back in.
Blue:
I wanted to add in more blue creatures as per suggestions here. I'll probably do it in the next update.
Out: Voidmage Prodigy
In: Kira, Great Glass Spinner
The wizard didn't unmorph even once. Kira seems to be a playable blue three drop with a useful effect.
Out: Sea Drake
In: Wonder
I wanted to make this change a long time. Sea drake didn't fit its color well; Wonder is a defensive four-drop that's easily discardable in its color.
Out: Faerie Trickery
In: Future Sight
I must admit that without the continuous praising of the cards by pretty much every cube owner here I wouldn't have even considered it. Here we probably underrate it, but I'm going to try anyway. Faerie Trickery costs much for a counter. For this cost, it should better be all-upside and strictly better than Cancel.
Out: Mystical Teachings
In: Crystal Shard
Crystal shard proved to be unplayable in non-blue deck so it moved to the blue section. MysticalTeaching costs too much and isn't very interesting.
Black:
Out: Zombify
In: Diabolic Servitude
Pure upgrade?
Out: Skittering Skirge
In: Phyrexian Rager
Skittering Skirge just underperformed each time. I wish I could've said that it is because black is so aggressive (it's not, and IMO it's too controllish right now) but it underperformed in control decks, and that's a sign it should get out. Phyrexian Rager should fill its curve slot well for all kinds of black decks as a cantripping 3 drop.
Out: Order of the Ebon Hand
In: Twisted Abomination
Following the white knight that got kicked before it, Order of the Ebon hand lost it's spot because of the redundancy in the 3 "pump knighs". It was played only by mono-black decks anyway, so it's not a great loss. The Abomination is a card planted for reanimation decks, as a self-cycler fattie that helps overcome mana problems.
Red:
Out: Urza's Rage
In: Resounding Thunder
This change was discussed here recently, and I agree that Resounding Thunder has a realistic chance to get cycled, unlike Urza's unwelcoming emotion. The "cannot be countered" part is not too relevant in our cube, control isn't that powerful that ramp decks cannot reach 8 mana before losing.
Out: Shock
In: Arc Lightning
I think that any deck who ever played shock would have preffered Arc Lightning instead.
Out: Brute Force
In: Starstorm
Another cube staple finally getting in. Brute Force is outclassed by all the burn spells in it's color.
Out: Form of the Dragon
In: Crater Hellion
Form of the Dragon didn't have enough support in red. Red is pretty diverse and fun now, so I don't think I need to support it. I play Caldera Hellion, so I can obviously play its big brother.
Green:
I've been trying to make ramp decks a top-tier deck. They are certainly playable now but they are not winning enough high places. Last update I added a lot of acceleration, but it still didn't help. This update, I noticed some decks did ramp up mana, but then they didn't have enough quality drops. The drops should be around 4-6. Since I had already pretty much covered my 4th drop most of the changes were adding 5 and 6 drops.
Out: Ghazban Ogre
In: Farhaven Elf
Since green aggro is already thriving and has too many cards, I cut one of the weaker aggressive drops for another accelerator, the only one this update.
Out: Jade Leech
In: Rhox Charger
Upgrade. Green fatties really need their trample (and shroud).
Out: Hurricane
In: Arashi, the Sky Asunder
This is almost an upgrade anyway, as instant speed and uncounterability do make the extra green mana worth it, and especially so if it comes with a fat body with a useful ability.
Out: Roar of the Wurm
In: Mycoloth
Mycoloth was hyped here and Roar of the Wurm underperformed.
Out: Witherscale Wurm
In: Weatherseed Treefolk
Trample. Green fatties need trample, and recursion is nice as a pseudo-shroud. Triple green is intimidating but still probably better than Witherscale Wurm.
Out: Summoner's Pact
In: Chord of Calling
Another upgrade. Chord toturs non-green creatures and put them into play. Again triple green, but convoke will probably make it easily affordable.
Out: Wren's Run Vanquisher
In: Stunted Growth
Vanquisher was a last try of tribal cards. It's failed as all the other did. Stunted Growth is a new direction for midrange decks - big sorceries. Plow Under is very solid, so this could be too. Usually green can replay it for a devastating effect.
Multicolored:
Out: Grixis Charm
In: Crosis's Charm
Upgrade
Out: Godhead of Awe
In: Deft Duelist
Godhead of Awe is outclassed by the high drops in both of its colors. As more and more time passes I expect fewer avatars to stay in. Deft Duelist would definitely see more play. I'm not hot about it, but it can play a good defender in UW control, and maybe even to go on the offense in a White-wenee based deck, carrying big equipment to victory.
Out: Safewright Quest
In: Phantom Nishoba
Safewrifght Quest is a wasted slot. I waited so much for replacing it because I've tried pretty much all the other W/G cards and they failed (Saffi, Gaddock Teeg, Wilt-Leaf Cavaliers...). I missed this one, so in it goes.
Artifact:
Out: Pithing Needle
In: Epochrasite
Pithing Needle seems solid because it can hit so many different permanents. In practice though naming Oona isn't going to solve your problems with the 5/5 flier and naming 8.5 tails is card disadvantage, as he got a 2/2 creature for WW. A friend of mine told me long time ago to take it out, he was right all the way.
Epochrasite seems like a fun card that'll make it to basically all non-aggro decks. It's happy with a blink effect.
Out: Crucible of Worlds
In: Triskelavus
Crucible of Worlds is narrow. It has some sick interactions, but in a big cube the chance you'll draft it + Strip Mine/ Wasteland is slim. In a big cube, those lands may not even be in your pod, so why the hell would anyone pick it unless he already has the aforementioned lands. And still he'd prefer a burn spell if he cannot tutor the combo. Triskelion and Puppet were solid, so perhaps I do have enough space for all three.
Out: Mox Diamond
In: Stuffy Doll
Mox diamond's card disadvantage made it bad. Stuffy Doll is another card aimed for midrange strategies. It can be a lot of fun with red.
Out: Crystal Shard
In: Sigil of Distinction
Crystal shard proved to be unplayable in non-blue decks so it moved to the blue section. Most of the haters of Sigil are small cube owners, so I guess it can make the cut in my cube.
Lands:
Out: Shelldock Isle
In: Riptide Laboratory
I saw that many extended decks use Riptide Laboratory and in the cube I play all the targets anyway so it's worth a try.
Jitte is nuts, but not as much. It requires you to have creatures out and damaging, which makes him more situational (sounds funny but true in some decks with few creatures or against them. Still always worth running, of course) and his effect isn't as crippling. Jitte is weaker than Skullclamp in our local opinion, who requires you only to have creatures out there, and yet even it cannot compare to LoA.