Cards to consider:

• Cyclonic Rift
• Teferi, Temporal Archmage
• Ashnod's Altar can combo with mikeaus, the unhallowed and any creature like Grey Merchant of Asphodel
• Ancient Tomb
• AEther Vial

COUNTERSPELLS

Sorry forgot to mention, Ashnod's Altar + Nim Deathmantle and Mikaeus, the Unhallowed

I have a couple of suggestions on what to remove.

Firstly, I would cut Expedition Map. It doesn't actually ramp at all and you don't need any of your lands to combo with. Arena of the Ancients is very powerful in your deck when you can continually untap your commander.

Also Arcane Sanctum is not legal in your deck so that needs to come out. Put another land in in the slot.

Cauldron of Souls is good, but it doesn't actually combo with Triskelion, as when he returns, he will not have persist again, and Cauldron of Souls can only be activated once per turn. Therefore I think it should come out too. Risen Executioner is another lord and can potentially combo.

Mind's Eye is really expensive, and I feel like an Underworld Connections would serve you better in this slot.

Cackling Counterpart is a worse Rite of Replication. And either way, I feel like you don't actually need copy effects in this deck. I'd either go with Rite of Replication or another sweeper such as Mutilate.

Lastly, Fatestitcher doesn't seem like it really does much in this deck. A Hoodwink could replace it as a way to get back you Rooftop Storm is it getds removed or countered.

Thank you for the feedback!

I'll replace Arcane Sanctum with dual.

Good point on Cackling Counterpart - I never thought about it that way. I'll probably bring in an Damnation instead, though I'm sad miss the opportunity of putting in 5 masters ;)

Thanks for pointing out that Cauldron of Souls + Triskelion does not go inf. I'll consider removing it, even though I really like that it can protect my board presence.

In my experience Mind's Eye is worth the wait, since it scales so well. I'll keep it over Underworld Connections.

I had Expedition Map in the mix for fetching Vesuva, Urborg, Tomb of Yawgmoth, or Cabal Coffers depending on which were allready in play. I guess I can trade it for a recursion spell, though I prefer Recall or Crystal Chimes over Hoodwink

I completely overlooked Risen Executioner - he is definitely going in. Master AND recursion - just what I need... he could be a nice replacement for Reassembling Skeleton

You are right about Fatestitcher -- he is out.

I'll consider adding an Ancient Tomb, but that means stretching my colorfixing.

Cheers

You could probably get away with running both Xiahou Dun, the One-Eyed and Living Death for another combo option with Phyrexian Altar and general added value

I thought Rooftop Storm only replaces the colorless part of the cmc. So it actually means you can cast zombies for free?

yes.

Weird. I wonder why it's not worth more. It has a high cmc, but still.

Added Ashnod's Altar and Grave Titan for another combo

You may want to consider Glen Elendra Archmage + Mikaeus, the Unhallowed for some control. It creates a counter wall. The deck looks like a lot of fun!

@The_Gaga_Gecko great suggestion. Even though she is not a zombie, she is just about powerful enough to add. What would you cut for her?

I'm considering adding Phylactery Lich since I run a lot of artifacts. Would Worldslayer be advisable?

I would cut Ancient Tomb for her as you have more than enough land and the damage is only gonna be self-deprecating in the long run.

@The_Gaga_Gecko I made the swap you suggested. What do would you consider enough lands?

Technically, lands are supposed to be 40 percent of a deck. That means you should have 40 lands in an EDH deck. However, I've found that the healthiest amount of lands for EDH is from 35-38. With the majority of you cards 3 drops, you should be golden with 37 lands. Couple tips for your mana base: swap out the duals that enter the battlefield tapped with something like River of Tears of Underground Sea, depending on your budget.

Sorry if I'm not clear, but I meant duals like the Guildgate that enter the battlefield tapped with no other effect.

Polluted Delta?

Since you have both Mikaeus and the Cauldron I would cut entomb (it is mainly effective with fetching gravecrawler, but since have other fetchers too I would not be too worries about that) and add Power Conduit or Hex Parasite. Both allow you to keep your creatures in play since you can the remove counters.

I would not be too concerned about what you mentioned as your flaw: spot removal. Your deck is powerful (in fact, I think I might give it a try, it looks really fun so +1 from me :) ) having a (small) flaw in the deck generally adds to the fun of both you and your opponent :)

Good work!

Never take Ancient Tomb out. It puts you one turn ahead of the curve; the loss of life is completely irrelevant. Every experienced EDH player will tell you that life is just another resource. The first 39 are free.

Plus, you're only playing two colors. Color fixing shouldn't be that big of a deal. Play City of Brass or Mana Confluence if you need to. You're priority over time, however, should be to take out all the lands that come in tapped. In tournaments, a land that enters tapped can mean the difference between victory and loss.

@The_Gaga_Gecko I only own one Underground Sea, and that is in use in a nother deck. I don't feel like investing in another one for this deck. The reason I am running all the duals is to ensure that I always have black mana in the mix, -I really don't want to start the game with a couple of islands. I can probably replace a couple of the worst with City of Brass and Mana Confluence, as suggested by MetalDivinity.

@GobboE thank you for the suggestions. I think I'll pass on the counters manipulation, as the suggested cards are somewhat situational and they won't allw me to go infinite (...and the parasite is not a zombie ;)).

@MetalDivinity Ancient Tomb is still under consideration. I think I'll bring it in instead of Dark Prophecy.

Shield of the Avatar can get stupid value when equipped to Grimgrin, Corpe-Born, depending on how many creatures/Zombie tokens you have out.

Srsly. Living Death and Patriarch's Bidding

I'm surprised you don't have Rise of the Dark Realms in here.

I'd sideboard an Undead Alchemist so you can spawn zombies if you need to.