I haven't played much 2HG EDH but a store near my area once had an event with predefined teams.
The most broken option we thought of was Zur, the enchanter with Niv-Mizzet, the firemind both focused on the idea that if you run either curiosity/ophidian eye (or both) you literally always start with the combo in the command zone so it's just a matter of time until the game ends. Both decks focused heavily on cheap card card draw/disruption/tutors/ramp so we could assemble the commander duo or just storm the other team and finish the game with something like tendrils of agony, mind over matter, doomsday or laboratory maniac.
Funny part was that we killed quite a bunch of people even before we had mana to cast Niv.
Just pointing out that Summoner's Pact can only fetch green creatures so unless you want it as another lotus petal (fetching elvish spirit guide) or to fecth lotus cobra and ramp in some wierd way it's probably not worth including.
I've been following this thread for quite a while and there's an argument I've never seen in the Recurring Nightmare discussions.
If you have Xiahou Dun, the One-Eyed and Victimize you get pretty much the same effect provided by Recurring Nightmare (your creatures will come into play tapped and you can only do that before your combat phase but I'm don't believe these differences are relevant most of the time).
Being two cards instead of one makes it harder to work if you are playing something like Karador, Mimeo or Jarad but with Xiahou Dun as your general is pretty easy to pull of (just need a single tutor) and even if you can't loop Eternal Witness, Acidic Slime or whatever non-black creature you want, you can use it to test RN scenarios like the one Cryo mentioned a couple posts back (Kokusho and Gray Merchant) that may scare some players.
I've used that interaction in my Xiahou Dun list for a while and that doesn't seem worse than Chainer loops or Buried Alive into Living Death for Trikelion and Mikaeus or stuff like that.
I agree with Moxnix, the mana base is so good I see no reason to run pure UB isntead of splashing for a few powerful cards like Nature's Claim or Wheel of Fortune.
Here's the lis if anyone wanna take a look (it's really similar to the list Moxnix posted btw):
But that's never going to happen in the real way.
Sure mana serevance exists but it not the same thing as running a deck with just a single land =(
The most broken option we thought of was Zur, the enchanter with Niv-Mizzet, the firemind both focused on the idea that if you run either curiosity/ophidian eye (or both) you literally always start with the combo in the command zone so it's just a matter of time until the game ends. Both decks focused heavily on cheap card card draw/disruption/tutors/ramp so we could assemble the commander duo or just storm the other team and finish the game with something like tendrils of agony, mind over matter, doomsday or laboratory maniac.
Funny part was that we killed quite a bunch of people even before we had mana to cast Niv.
If you have Xiahou Dun, the One-Eyed and Victimize you get pretty much the same effect provided by Recurring Nightmare (your creatures will come into play tapped and you can only do that before your combat phase but I'm don't believe these differences are relevant most of the time).
Being two cards instead of one makes it harder to work if you are playing something like Karador, Mimeo or Jarad but with Xiahou Dun as your general is pretty easy to pull of (just need a single tutor) and even if you can't loop Eternal Witness, Acidic Slime or whatever non-black creature you want, you can use it to test RN scenarios like the one Cryo mentioned a couple posts back (Kokusho and Gray Merchant) that may scare some players.
I've used that interaction in my Xiahou Dun list for a while and that doesn't seem worse than Chainer loops or Buried Alive into Living Death for Trikelion and Mikaeus or stuff like that.
I agree with Moxnix, the mana base is so good I see no reason to run pure UB isntead of splashing for a few powerful cards like Nature's Claim or Wheel of Fortune.
Here's the lis if anyone wanna take a look (it's really similar to the list Moxnix posted btw):
http://tappedout.net/mtg-decks/enchanter-10/
http://tappedout.net/mtg-decks/no-ban-list-edh/
The list isn't perfect but I should be mostly it.