This is just something that I've been toying with recently. The idea is to give the deck more consistency by having more mana dorks to cast six drops. In testing I've been consistently able to cast a face up Sagu Mauler or Doom Engine on turns 3/4. Icefeather Aven has been exceptional against the green devotion decks and Abzan Midrange.
Your deck as it currently stands looks like your running a weaker version of Grave Titan as your commander. Sidisi's strength lies in her ability to get cards into your graveyard, and if you abuse that ability, it's like getting a free Ancestral Recall every time she attacks. The zombies are just a bonus and means that Sidisi will be able to take over the game herself if you have a high creature density in the deck.
I would personally replace all the additional mill cards for more recursion. Genesis and Oversold Cemetery are strong reusable options. Reanimate, Animate Dead, Archeomancer, Regrowth are cheap one shot effects. Having a fair amount of recursion along with Sidisi's mill allows you to basically use your graveyard as an extension of your hand.
I'd recommend some protection for Sidisi aswell. Your stock standard Lightning Greaves and your not so standard Sylvan Safekeeper are some options for protection.
- Dragon Fodder and Krenko's Command helps immensely in speeding up the production of your goblin army.
- Lightning Mauler, Hall of the Bandit Lord, Hellraiser Goblin]/card] and Goblin Rabblemaster are all haste effects that curves into Krenko. The last two are riskier but are also goblins. Ogre Battledriver is also a great buff and haste effect for the army.
- Ancient Tomb and Ruby Medallion gets you to Krenko a turn earlier, only real drawback being the price of the cards.
- Marton Stromgald is basically Craterhoof Behemoth in red.
- I'm not sure where you are on infinite combos but Kiki-Jiki/Zealous Conscript is an infinite combo. Breath of Fury could potentially give you infinite attack steps.
- Seeing how Krenko's only real weakness is wrath effects, you should pack as many of the better ones as you can and Eldrazi Monument is one of the best. Moderately priced but very strong for any Krenko deck.
- Taurean Mauler is technically a goblin that can add a ton of pressure early on and can forces opponents to answer this instead of Krenko. Additionally Mutavault is also a "goblin" man land but is pricey.
- Tuktuk Scrapper Artifact removal on demand and is also a goblin.
- Valakut, the Molten Pinnacle and Koth of the Hammer can just as easily close the game as Krenko and the goblin army.
- Mask of Memory, Skullclamp, Slate of Ancestry, Sensei's Divining Top, Sword of Fire and Ice and Sword of Light and Shadow are fantastic card advantage avaialable to red. The slate is expensive to cast and activate while the Swords and top are just plain expensive. If you do add some/all of these, consider also adding Godo, Bandit Warlord.
- Being mono colored means that you can be greedier with your manabase and still have plenty of colored mana available. I would suggest Nykthos, Shrine to Nyx, Buried Ruin and Haunted Fengraf. Strip Mine and Wasteland et al are also pretty handy to have around just in case someone plays a cradle.
- I'm personally a big fan of Burn at the Stake but it can be a bit clunky at times due to its high mana cost. Also Chaos Warp is fantastic catch all removal for red.
As for cuts:
- Gratuitous Violence and Rage Reflection only work well when you have another anthem effect running, otherwise both are very lackluster for the cost.
- Crystal Ball is more often than not a waste of mana and any draw effect is much stronger.
- Goblin Grenade doesn't do enough in multiplayer commander to warrant a spot.
- Doom Cannon, Fodder Cannon and Goblin Charbelcher don't do anything offensive and can't kill the creatures that really matter like Iona, Shield of Emeria or Elesh Norn, Grand Cenobite.
- Gorgon's Head works well with some of your creatures, but getting them dead is more important than doodling around with this card.
- Not a fan of Sarpadian Empires or Swiftfoot Boots because both are just too slow for what your trying to accomplish with Krenko.
- Goblin Tinkerer is often a turn too slow without any haste effect and normally just trades with the artifact, not very good.
- Bloodmark Mentor isn't relevant as first strike rarely matters in commander and Clickslither just makes it easier to stem your aggression by killing off one creature as opposed to a horde.
- Not a fan of Ib Halfheart either, the later the game goes the more lands you'll need because Krenko tends to die..a lot.
- Teetering Peaks is useless when your just trying to swarm your opponent and it coming into play tapped could slow you down a turn, not worth the trade.
In general, Krenko is a very one dimensional commander so look at the other Krenko lists posted here to get a better idea of what to add or cut.
I've always found the mill option to be a solid plan B mainly because you will more than likely be the only one trying to attack them through mill while everyone else is trying to win through damage. This makes it extremely difficult for you as you cannot continue from the hard work of others when trying to eliminate an opponent. Furthermore if any of your opponents have an Eldrazi in their decks, it's pretty much over for plan A.
As for cuts, I think the first thing you need to cut is most of your targeted mill effects. The only ones that are truly worth running and are genuine threats are Traumatize, Jace, Memory Adept and Altar of Dementia. An exception can also be made for Archive Trap as it messes up the 'to the top of your library' tutor cards and basically costs 0. Also the milling enchantments are much too insignificant in a typical game of Commander to be anything more than a waste of space.
Beyond that you may want some more control as your primary game plan is extremely slow, so slowing down the game in whatever way possible will be necessary to extend the time you have to carry out your game plan. Mass removal such as Damnation and solid catch all counterspells like Hinder will do wonders as support for the mill strategy.
Finally I would suggest The Mimeoplasm as a potential general as it gives you access to green which is arguably the strongest colour in Commander and works particularly well with both self mill and milling opponents. Green also gives access to efficient and recurrable draw such as Sylvan Library, Greater Good as well as huge green beaters like Lord of Extinction. You also mentioned that your meta consists of a lot of ramp decks which means there will be no shortage of juicy targets for Mimeoplasm to borrow. In short Mimeoplasm is a fun and versatile general that can be both proactive and reactive.
As you are running a ton of cards that allow you to play extra lands, I would suggest increasing your land count. This ensures that you will have less chance of missing land drops and thus being able to consistently cast Damia early on. Sunder works well with these cards as you will recover faster than your opponents and using it after a overloaded Cyclonic Rift is just brutal.
Terastodon and Woodfall Primus are great cards in general for any green deck but they also supplement that minor land destruction theme you have going on. If you want to expand on that theme I would also suggest Frost Titan and Beast Within as they can lockdown or destroy any pesky permanents bothering you. Rite of Replication and Progenitor Mimic work well with these cards but are also fantastic cards in their own right.
I would also suggest more mana ramp such as Mana Reflection and Boundless Realms as it will allow you to better utilize Damia's abilities by being able to cast all the cards you've drawn with Damia and thus being able to draw more!
I would suggest loading up on planeswalkers because the crazy snake lady is one of the best general to protect planeswalkers in multiplayer as people will rarely want to attack into flash deathtouch snakes. Pretty much all the Garruk's will gain you a huge advantage and can potentially win the game on their own.
A fun little card that I've been toying with recently is Angel's Trumpet. Again due to the nature of your general, attacks will rarely be directed at you, and this plays well into your general as you force others to attack and therefore can somewhat control what creature lives or dies by giving the defending player a snake.
Since your in black, a good way to keep the control players in check is through discard. You already have access to Sadistic Hypnotist, another card that is just as good is Mind Slash. Nath of the Gilt-leaf and Hypnotic specter are also great single target discard creatures that will not earn the ire of the entire table.
Necropotence and Dark Prophecy are some of the best draw options available in golgari. Furthermore since you have a large range of creatures that can deal with various scenarios, Survival of the Fittest and/or Fauna Shaman can help you fetch those creatures when the need arises.
I also personally like more utility ETB creatures such as Bone Shredder, Big Game Hunter and Shriekmaw. Utility creatures such as these fly under the threat radar and if you have a decent board position, a good overrun effect can turn these seemingly benign creatures into game winning threats.
Since aDubiousNotion have made many fantastic suggestions. You might want a second opinion on what to cut: Abhorrent Overlord - This card is much too reliant on having a good board position to be effective. Even then there are better options at 7 CMC. Bane of the Living - This card can do more harm than good for your army of weenies, also you have enough creature control that this should not be necessary. Drana, Kalastria Bloodchief and Hythonia the Cruel - Requires too much mana and is a huge threat. Will probably die before your able to use their effects. Fleshbag Marauder and Slum Reaper - may not give you your desired result as they may have a snake or two they can sacrifice. Extractor Demon - Your not a mill deck thus making this a generic big beater. Not great in 4-6 player commander. Indrik Stomphowler - You've already got a decent amount of artifact/enchantment removal on a stick, this is just redundant and expensive to cast. Erebos, God of the Dead - I would only use this if your playgroup has decks that gain a ton of life, Otherwise I'd stick to a better card advantage effect. Pestilance Demon and Steel Hellkite - These cards are expensive and don't do anything relevant in this deck. There are better options if you are looking for similar effects. Seedborn Muse - You don't have any cards that work well with Seedborn Muse. No relevant instants or instant abilities. Leyline of Vitality - a 1/2 or 2/3 etc won't be able to survive against many of the creatures in commander. The lifegain is OK, but not worth the card slot. Living Death et al - You don't have a strong self mill theme going, making these types of cards a hit or miss. I know these works well with Pharika but it will take too much time to set up the desired effect. Putrefy - Should be Beast Within unless your truly afraid of regenerate. Restock - While this card provides more value than Regrowth, Regrowth allows you to use it and the card you got back on the same turn. Lifeline - Too narrow as it does not allow you to return creatures that are already in your graveyard. Altar of Dementia and Sword of Body and Mind- Again your deck doesn't benefit from milling much. Thornbite Staff - Not sure what this card is supposed to be comboing with here. Golgari Cluestone - You have alot of 3 and 4 drops, making this ramp a bit awkward on your curve.
Thanks for the heads up on the Bottled Cloister and Ensnaring Bridge combo. Still the sum of both parts is a very weak combo at best and is easily disrupted with dire consequences. Individually both cards can easily work against you, while you only gain a small benefit from their effects.
At the moment your deck lacks any semblance of synergy with your general and other cards. Let's start with a few cards that doesn't work with Olivia.
Devastation, Jokulhaups et al - Olivia requires alot of mana or multiple turns to use her ability effectively. By using these cards, your essentially turning your general into a generic 3/3 flying for 4.
Death Pits of Rath - Unlike Basilisk Collar and Gorgon Flail, this card completely invalidates her ability to steal creatures as you have no effective method to 'turn it off'.
Ill-gotten Gains and Spiteful Vision - When your ahead with Olivia, you really don't want to be able to give your opponents the chance to destroy your board position by removing Olivia. Use Yawgmoth's Will and Xiahou Dun, the One-Eyed if you want some recursion.
Some other cards that I think are just bad in general for this deck.
Anathemancer - either use this and Price of Progress or MLD, using both is counterintuitive.
Goblin Sharpshooter - your general is Olivia, your in black AND red, goblin sharpshooter is just overkill.
Guiltfeeder - is a generic fatty that is greatly diminished by graveyard removal. Grave Titan and Lord of the Void are also big beaters but have the potential to do alot more.
Erebos and Mogus - one is worse than Greed and the other does nothing significant and could potentially help the opponent. If you want more card advantage, there are plenty of phyrexian arena esque creatures such as Graveborn Muse and Bloodgift Demon.
Kiki-Jiki and Sheoldred - these are both powerful cards, but in order to make their inclusion worth it, you will need more cards that interact with their abilities.
Tymaret - if your just looking for sacrifice outlets, there are better options than this. Goblin Bombardment, Phyrexian Tower, High Market and Trading Post are either harder to remove, have broader range or take up less space.
Chandra Nalaar - the +1 and -X are insignificant in commander and her ultimate only affects one opponent making her one of the worst planeswalkers. Karn Liberated and any of the other chandra's are better.
Bottled Cloister - I don't get why this card is in your deck, I may have missed a combo with it or something. If there is no combo then this card is very risky with little gain, Mind's Eye is a much stronger card.
Ensnaring Bridge - don't really get why you included this card when your main avenue to victory is through the combat phase. If you want a rattlesnake effect, use No Mercy or Wound Reflection to make it more enticing to attack somone else.
Ring of Xathrid - any of the Swords of X and Y (chief among them is Sword of Feast and Famine) is better than this card. If your looking for additional protection, Darksteel Plate is much better.
Rings of Brighthearth - costs too much to use efficiently. I would rather use Heartstone or another mana rock in it's place.
Increasing vengeance - an instant or sorcery YOU control. This card is just too narrow, if you want a similar effect Wild Ricochet or just good old Fork have broader range.
If you intend to go the mass land/creature destruction route, I would add some cheap reanimation cards, Reanimate and Necromancy. Braid of Fire and Black Market are not removed and can help you get back on your feet faster than the other players. Bitterblossom and Goblin Assault adds alot of pressure after clearing the board. Planeswalkers are also a great way to remain ahead post Devastation. Some other cards to consider if you are going this route are Obliterate and Decree of Annihilation.
I personally like versatile discard cards in Olivia. Coupled with all the removal and artifact hate that red and black has to offer, there should be little to no board presence for anyone, and when players have little to no resources on the board or in hand, Olivia reigns supreme!
These cards all serve as powerful discard options, and will also function effectively when everyone inevitably goes into topdeck mode. I wouldn't go overboard with the discards as black has numerous tutors that can find them if necessary.
Rapacious One feels tailor made for Purphoros to abuse. The tokens can then be used to pump Rapacious One (via Purphoros) for more tokens!
No Goblin Bombardment? It's one of the best sacrifice outlets available to red for obvious reasons.
Considering the amount of artifacts you run, Trading Post seems like a good addition to the deck. It cycles your mana rocks in the later portions of the game, shocks everyone every turn and recurs important artifacts your opponents want gone.
Seeing as most of the best red token generators also have something to do with goblins, you could add a goblin subtheme to the deck. A benefit of this is that it also adds consistency to the deck with tutors such as Moggcatcher (put into play!), Goblin Recruiter and Goblin Matron. This opens you up to add cards like Krenko, Mob Boss and Ib Halfheart, Goblin Tactician as well as the goblin lords of which there are many. This provides a strong alternate win con if your general ever gets tucked.
If your in the market for another haste enabler, In the Web of War stands out the most just because it's so strong with Prossh and other mass token generators. Speaking of token support, Coat of Arms was THE card back in the days to support tribal and token themed decks and is still one of the best options available for token decks.
Seeing as you have so many sac outlets, have you considered using more threaten effects as point removal spells? Both Beast Within and Putrefy have additional uses but terminate can easily be replaced to gain some additional value. Something like Word of Seizing if you wish to remain with more instant speed removal or Zealous Conscripts for some recursion.
Additionally if your consistently playing in 4 man games, Syphon Mind becomes a strict upgrade over Harmonize. A card that has slipped my mind and is very strong with Prossh is the new M14 black enchantment Dark Prophecy. Both Staff of Nin and Deadbridge Chant are good conspicuous card draw effects that don't draw much hate. Terastodon is both a fast clock and an amazing noncreature removal spell. Gaze of Granite is a fair replacement for Pernicious Deed with the additional benefit of also destroying Planeswalkers. Damnation and Decree of Pain are upgrades over Black Sun's Zenith and Life's Finale, especially if your not abusing Life's Finale's second ability. Primeval Bounty might also be worth looking into.
4 Ornithopter
4 Elvish Mystic
2 Chief Engineer
3 Phyrexian Revoker
4 Icefeather Aven
3 Rattleclaw Mystic
3 Scuttling Doom Engine
4 Sagu Mauler
2 Stubborn Denial
2 Springleaf Drum
4 Ghostfire Blade
4 Ensoul Artifact
1 Bident of Thassa
Lands 20
4 Mana Confluence
4 Yavimaya Coast
4 Darksteel Citadel
4 Island
4 Forest
This is just something that I've been toying with recently. The idea is to give the deck more consistency by having more mana dorks to cast six drops. In testing I've been consistently able to cast a face up Sagu Mauler or Doom Engine on turns 3/4. Icefeather Aven has been exceptional against the green devotion decks and Abzan Midrange.
A White splash for Sorin, Solemn Visitor gives you presence against sweepers and allows you to race other aggro.
A Red splash for Goblin Rabblemaster a stronger 2 drop in War-Name Aspirant and burn to close games.
I would also play Thoughtseize.
Red - you have your usual suspects in Goblin Rabblemaster and Stormbreath Dragon.
Blue - Soul of Ravnica shouldn't be overlooked.
Black - ...maybe next set
Multicolor - Keranos, God of Storms looks good in theory, deserves to be tested atleast.
I would personally replace all the additional mill cards for more recursion. Genesis and Oversold Cemetery are strong reusable options. Reanimate, Animate Dead, Archeomancer, Regrowth are cheap one shot effects. Having a fair amount of recursion along with Sidisi's mill allows you to basically use your graveyard as an extension of your hand.
Mystic Snake, Voidmage Husher, Venser, Shaper Savant and Glen Elendra Archmage are easily recurrable disruption. Prophet of Kruphix alongside other disruptive creatures such as Shriekmaw will grant you a lot of control.
I'd recommend some protection for Sidisi aswell. Your stock standard Lightning Greaves and your not so standard Sylvan Safekeeper are some options for protection.
- Lightning Mauler, Hall of the Bandit Lord, Hellraiser Goblin]/card] and Goblin Rabblemaster are all haste effects that curves into Krenko. The last two are riskier but are also goblins. Ogre Battledriver is also a great buff and haste effect for the army.
- Ancient Tomb and Ruby Medallion gets you to Krenko a turn earlier, only real drawback being the price of the cards.
- Marton Stromgald is basically Craterhoof Behemoth in red.
- I'm not sure where you are on infinite combos but Kiki-Jiki/Zealous Conscript is an infinite combo. Breath of Fury could potentially give you infinite attack steps.
- Seeing how Krenko's only real weakness is wrath effects, you should pack as many of the better ones as you can and Eldrazi Monument is one of the best. Moderately priced but very strong for any Krenko deck.
- Taurean Mauler is technically a goblin that can add a ton of pressure early on and can forces opponents to answer this instead of Krenko. Additionally Mutavault is also a "goblin" man land but is pricey.
- Tuktuk Scrapper Artifact removal on demand and is also a goblin.
- Valakut, the Molten Pinnacle and Koth of the Hammer can just as easily close the game as Krenko and the goblin army.
- Mask of Memory, Skullclamp, Slate of Ancestry, Sensei's Divining Top, Sword of Fire and Ice and Sword of Light and Shadow are fantastic card advantage avaialable to red. The slate is expensive to cast and activate while the Swords and top are just plain expensive. If you do add some/all of these, consider also adding Godo, Bandit Warlord.
- Being mono colored means that you can be greedier with your manabase and still have plenty of colored mana available. I would suggest Nykthos, Shrine to Nyx, Buried Ruin and Haunted Fengraf. Strip Mine and Wasteland et al are also pretty handy to have around just in case someone plays a cradle.
- I'm personally a big fan of Burn at the Stake but it can be a bit clunky at times due to its high mana cost. Also Chaos Warp is fantastic catch all removal for red.
As for cuts:
- Gratuitous Violence and Rage Reflection only work well when you have another anthem effect running, otherwise both are very lackluster for the cost.
- Crystal Ball is more often than not a waste of mana and any draw effect is much stronger.
- Goblin Grenade doesn't do enough in multiplayer commander to warrant a spot.
- Doom Cannon, Fodder Cannon and Goblin Charbelcher don't do anything offensive and can't kill the creatures that really matter like Iona, Shield of Emeria or Elesh Norn, Grand Cenobite.
- Gorgon's Head works well with some of your creatures, but getting them dead is more important than doodling around with this card.
- Not a fan of Sarpadian Empires or Swiftfoot Boots because both are just too slow for what your trying to accomplish with Krenko.
- Goblin Tinkerer is often a turn too slow without any haste effect and normally just trades with the artifact, not very good.
- Bloodmark Mentor isn't relevant as first strike rarely matters in commander and Clickslither just makes it easier to stem your aggression by killing off one creature as opposed to a horde.
- Not a fan of Ib Halfheart either, the later the game goes the more lands you'll need because Krenko tends to die..a lot.
- Teetering Peaks is useless when your just trying to swarm your opponent and it coming into play tapped could slow you down a turn, not worth the trade.
In general, Krenko is a very one dimensional commander so look at the other Krenko lists posted here to get a better idea of what to add or cut.
As for cuts, I think the first thing you need to cut is most of your targeted mill effects. The only ones that are truly worth running and are genuine threats are Traumatize, Jace, Memory Adept and Altar of Dementia. An exception can also be made for Archive Trap as it messes up the 'to the top of your library' tutor cards and basically costs 0. Also the milling enchantments are much too insignificant in a typical game of Commander to be anything more than a waste of space.
Beyond that you may want some more control as your primary game plan is extremely slow, so slowing down the game in whatever way possible will be necessary to extend the time you have to carry out your game plan. Mass removal such as Damnation and solid catch all counterspells like Hinder will do wonders as support for the mill strategy.
Finally I would suggest The Mimeoplasm as a potential general as it gives you access to green which is arguably the strongest colour in Commander and works particularly well with both self mill and milling opponents. Green also gives access to efficient and recurrable draw such as Sylvan Library, Greater Good as well as huge green beaters like Lord of Extinction. You also mentioned that your meta consists of a lot of ramp decks which means there will be no shortage of juicy targets for Mimeoplasm to borrow. In short Mimeoplasm is a fun and versatile general that can be both proactive and reactive.
As you are running a ton of cards that allow you to play extra lands, I would suggest increasing your land count. This ensures that you will have less chance of missing land drops and thus being able to consistently cast Damia early on. Sunder works well with these cards as you will recover faster than your opponents and using it after a overloaded Cyclonic Rift is just brutal.
Terastodon and Woodfall Primus are great cards in general for any green deck but they also supplement that minor land destruction theme you have going on. If you want to expand on that theme I would also suggest Frost Titan and Beast Within as they can lockdown or destroy any pesky permanents bothering you. Rite of Replication and Progenitor Mimic work well with these cards but are also fantastic cards in their own right.
I would also suggest more mana ramp such as Mana Reflection and Boundless Realms as it will allow you to better utilize Damia's abilities by being able to cast all the cards you've drawn with Damia and thus being able to draw more!
A fun little card that I've been toying with recently is Angel's Trumpet. Again due to the nature of your general, attacks will rarely be directed at you, and this plays well into your general as you force others to attack and therefore can somewhat control what creature lives or dies by giving the defending player a snake.
Since your in black, a good way to keep the control players in check is through discard. You already have access to Sadistic Hypnotist, another card that is just as good is Mind Slash. Nath of the Gilt-leaf and Hypnotic specter are also great single target discard creatures that will not earn the ire of the entire table.
Necropotence and Dark Prophecy are some of the best draw options available in golgari. Furthermore since you have a large range of creatures that can deal with various scenarios, Survival of the Fittest and/or Fauna Shaman can help you fetch those creatures when the need arises.
I also personally like more utility ETB creatures such as Bone Shredder, Big Game Hunter and Shriekmaw. Utility creatures such as these fly under the threat radar and if you have a decent board position, a good overrun effect can turn these seemingly benign creatures into game winning threats.
Since aDubiousNotion have made many fantastic suggestions. You might want a second opinion on what to cut:
Abhorrent Overlord - This card is much too reliant on having a good board position to be effective. Even then there are better options at 7 CMC.
Bane of the Living - This card can do more harm than good for your army of weenies, also you have enough creature control that this should not be necessary.
Drana, Kalastria Bloodchief and Hythonia the Cruel - Requires too much mana and is a huge threat. Will probably die before your able to use their effects.
Fleshbag Marauder and Slum Reaper - may not give you your desired result as they may have a snake or two they can sacrifice.
Extractor Demon - Your not a mill deck thus making this a generic big beater. Not great in 4-6 player commander.
Indrik Stomphowler - You've already got a decent amount of artifact/enchantment removal on a stick, this is just redundant and expensive to cast.
Erebos, God of the Dead - I would only use this if your playgroup has decks that gain a ton of life, Otherwise I'd stick to a better card advantage effect.
Pestilance Demon and Steel Hellkite - These cards are expensive and don't do anything relevant in this deck. There are better options if you are looking for similar effects.
Seedborn Muse - You don't have any cards that work well with Seedborn Muse. No relevant instants or instant abilities.
Leyline of Vitality - a 1/2 or 2/3 etc won't be able to survive against many of the creatures in commander. The lifegain is OK, but not worth the card slot.
Living Death et al - You don't have a strong self mill theme going, making these types of cards a hit or miss. I know these works well with Pharika but it will take too much time to set up the desired effect.
Putrefy - Should be Beast Within unless your truly afraid of regenerate.
Restock - While this card provides more value than Regrowth, Regrowth allows you to use it and the card you got back on the same turn.
Lifeline - Too narrow as it does not allow you to return creatures that are already in your graveyard.
Altar of Dementia and Sword of Body and Mind- Again your deck doesn't benefit from milling much.
Thornbite Staff - Not sure what this card is supposed to be comboing with here.
Golgari Cluestone - You have alot of 3 and 4 drops, making this ramp a bit awkward on your curve.
Devastation, Jokulhaups et al - Olivia requires alot of mana or multiple turns to use her ability effectively. By using these cards, your essentially turning your general into a generic 3/3 flying for 4.
Death Pits of Rath - Unlike Basilisk Collar and Gorgon Flail, this card completely invalidates her ability to steal creatures as you have no effective method to 'turn it off'.
Ill-gotten Gains and Spiteful Vision - When your ahead with Olivia, you really don't want to be able to give your opponents the chance to destroy your board position by removing Olivia. Use Yawgmoth's Will and Xiahou Dun, the One-Eyed if you want some recursion.
Some other cards that I think are just bad in general for this deck.
Anathemancer - either use this and Price of Progress or MLD, using both is counterintuitive.
Goblin Sharpshooter - your general is Olivia, your in black AND red, goblin sharpshooter is just overkill.
Guiltfeeder - is a generic fatty that is greatly diminished by graveyard removal. Grave Titan and Lord of the Void are also big beaters but have the potential to do alot more.
Erebos and Mogus - one is worse than Greed and the other does nothing significant and could potentially help the opponent. If you want more card advantage, there are plenty of phyrexian arena esque creatures such as Graveborn Muse and Bloodgift Demon.
Kiki-Jiki and Sheoldred - these are both powerful cards, but in order to make their inclusion worth it, you will need more cards that interact with their abilities.
Tymaret - if your just looking for sacrifice outlets, there are better options than this. Goblin Bombardment, Phyrexian Tower, High Market and Trading Post are either harder to remove, have broader range or take up less space.
Chandra Nalaar - the +1 and -X are insignificant in commander and her ultimate only affects one opponent making her one of the worst planeswalkers. Karn Liberated and any of the other chandra's are better.
Bottled Cloister - I don't get why this card is in your deck, I may have missed a combo with it or something. If there is no combo then this card is very risky with little gain, Mind's Eye is a much stronger card.
Ensnaring Bridge - don't really get why you included this card when your main avenue to victory is through the combat phase. If you want a rattlesnake effect, use No Mercy or Wound Reflection to make it more enticing to attack somone else.
Ring of Xathrid - any of the Swords of X and Y (chief among them is Sword of Feast and Famine) is better than this card. If your looking for additional protection, Darksteel Plate is much better.
Rings of Brighthearth - costs too much to use efficiently. I would rather use Heartstone or another mana rock in it's place.
Increasing vengeance - an instant or sorcery YOU control. This card is just too narrow, if you want a similar effect Wild Ricochet or just good old Fork have broader range.
If you intend to go the mass land/creature destruction route, I would add some cheap reanimation cards, Reanimate and Necromancy. Braid of Fire and Black Market are not removed and can help you get back on your feet faster than the other players. Bitterblossom and Goblin Assault adds alot of pressure after clearing the board. Planeswalkers are also a great way to remain ahead post Devastation. Some other cards to consider if you are going this route are Obliterate and Decree of Annihilation.
You should also fix your manabase by replacing some basics with Tainted Peak, Graven Cairns, Lavaclaw Reaches, Dragonskull Summit, Temple of Malice, fetchlands etc. Being in two colors also means you can be greedier and use more colorless utility lands, Winding Canyon, Ancient Tomb, Maze of Ith, Thawing Glaciers, Volrath's Stronghold, Strip Mine just to name a few.
Versatile discards:
These cards all serve as powerful discard options, and will also function effectively when everyone inevitably goes into topdeck mode. I wouldn't go overboard with the discards as black has numerous tutors that can find them if necessary.
As for red, I personally only use for artifact destruction and hate cards such as price of progress, anathemancer, stranglehold and trouble. Along with torpor orb these cards can win against broken combos and strategies.
No Goblin Bombardment? It's one of the best sacrifice outlets available to red for obvious reasons.
Considering the amount of artifacts you run, Trading Post seems like a good addition to the deck. It cycles your mana rocks in the later portions of the game, shocks everyone every turn and recurs important artifacts your opponents want gone.
Seeing as most of the best red token generators also have something to do with goblins, you could add a goblin subtheme to the deck. A benefit of this is that it also adds consistency to the deck with tutors such as Moggcatcher (put into play!), Goblin Recruiter and Goblin Matron. This opens you up to add cards like Krenko, Mob Boss and Ib Halfheart, Goblin Tactician as well as the goblin lords of which there are many. This provides a strong alternate win con if your general ever gets tucked.
If your in the market for another haste enabler, In the Web of War stands out the most just because it's so strong with Prossh and other mass token generators. Speaking of token support, Coat of Arms was THE card back in the days to support tribal and token themed decks and is still one of the best options available for token decks.
Seeing as you have so many sac outlets, have you considered using more threaten effects as point removal spells? Both Beast Within and Putrefy have additional uses but terminate can easily be replaced to gain some additional value. Something like Word of Seizing if you wish to remain with more instant speed removal or Zealous Conscripts for some recursion.