I'm also rather sad that there are a full 4 dread returns in the list, you only need to resolve one game 1 to cement a win, and games 2-3 they are often garbage since your yard is hated so much.  Whoever is using 4 dread returns, stop.  The freed up space will give you a stronger deck, 2 is enough.

I actually use a lone Sensei's Top in my build as well. I like that it can nab cards you stack with the topdeck tutors (Mystical, Vampiric, Imperial) to use "right now". The library manipulation is nice too in topdeck mode or with fetchlands.

I currently use 2/1 on the Chrome Mox/ Mox Diamond. Neither are stellar in the early game unless you're resolving an Ad Nauseam usually. In theory you just need to draw one black source to combine with Ritual effects etc. off a succesful Ad Nauseam. I also only use 2 Cabal Rits and run the full set of Moxen to compliment the early Ad. Ponder also is in my list.

A SB card that I really run a singleton copy of and like to use in a matchup with few win conditions (like Tezz) is Bitter Ordeal. Combined with my 6 fetch and Lotus Petal/ B. Lotus it often has at least 1 copy to add to the stack if not 2. Then again I've always had an irrational love of some "bad" cards.

This is an interesting point, but I think Bargain is wrong for this deck. There is a delicate balance of "bombs" that any deck can run and the upside of running "Draw X cards for X life" number 6 in this deck is not as good as the downside that you have a good chance of hitting it when you are drawing off Ad Nauseam.

I like everyone's suggestions so far and will be Tinkering with the decklist as I test it more.

I do think Pact Of Negation is a Red Herring and makes this deck in to a Goldfish deck that it simply cannot be in the current environment. Mystic Remora is a major reason that this deck can't run Pact Of Negation. Your Pact will not do much of anything for you against a resolved Remora. Thoughtseize can at least keep the standstill long enough for you to find Chain for the Remora.

I do like Xantid Swarm in the SB and agree that Academy should probably be cut, but how should the manabase look between MD and SB in that case? How many green sources MD and how many SB? (Academy is not useless in this deck as you'll often at least get to tap it for UU and often UUU and that can get you to 5 mana more quickly so you can cast Ad Nauseam in the first place.

I'm also curious to know what people think of Tinker/Robot plan from the SB. What would they come in for? Is Inkwell better than Sundering Titan for this deck?

1 MD Intuition might also be interesting to test with but I really don't see how I can fit it when I'm also running Confidants and keep the shell of the deck intact. Is dropping Confidant entirely an option?

The thing is guys, Confidant makes this deck play out a lot more like Stephens Grow deck that he played at Stratford on day 1 and Tarmogoyf from the SB really REALLY does. This deck can't try to do too many things well because otherwise it will do nothing well.

This is why I like Xantid Swarm. It supports the strategy of resolving Ad Nauseam and it is a house against Remora decks (one of this deck's weakest matchups if not THE weakest). I think Chains Of Mephistopholes could also be warranted from the SB but that is something I'll have to consider with regards to space. Confidant is a good choice but it is about as far as I'd go towards making this deck a "short burst" type of deck vs. a true "all-in combo" deck. The problem with short bursts against Drain decks featuring Vault/Key is that sometimes the "win small" approach will backfire when you give them the critical Time Walk they need to assemble the combo. Combo has gone from being a "win the turn before I die" type of deck to a "OMG I don't know if I have the gas to go off this turn so I'll do a mini-win and win later/ I'll wait a turn. Shit, one turn too late." Combo has no center or linearity to it any more and is beginning to die off and I think it is due to 5 factors:

1) No Brainstorm or Ponder
2) Faster Control Decks (Vault/Key)
3) Remora is first turn play and is better than its red counterpart: Pyrostatic Pillar
4) Combo is difficult to play so players play slow-play cards that are more easy to use like Confidant or Tarmogoyf to supplement (in actuality dilute) the gameplan.
5) Combo is difficult to play so players overcompensate by trying to make the deck "Goldfish" and thus ruin its ability to interact at different stages of the game. Combo should not = Turn 1 people.

I think 4 thoughtsieze is wrong.  I'm pretty sure the correct number is 0.  Pact of negation is better here because it doesn't cost you life and doesn't ping you when it's revealed and you're just going to use it to protect yourself when going off anyway.  If ad nauseam resolves on your turn you're not goign to have another upkeep most likely.  Life is a binding variable in this deck so you need to carefully consider any card with a life total effect.  Thoughtsieze will cost you more games through life loss in the long run I think than it will win.