…Better late than never, right? 
Sorry for the late weigh-in here, folks.  Real life sometimes gets in the way of doing the fun stuff, and today was one of those days to the extreme.  My apologies to those of you who tuned in at normal time.  I won’t delay any further…let’s dig right in.
I’m getting a ton of replies on this Xiahou Dun series from you readers, and I think it serves to keep the creative ball rolling, so I’m going to keep with the mailbag at the beginning here while I work my way through this deck.
From Dan:

Have you considered cycling in the deck? Xiahou Dun says black card to hand, not creature. That opens up design space.  There aren’t a ton of black cycling cards (20), but what’s there can be pretty good- Twisted Abomination to get swamps to power some of the Voltron equipment for example. Decree of Pain is just an all star. You can keep getting engines though, like Unearth or Undead Gladiator.

I tend to discount cycling as a whole, but I think this has merit.  Decree of Pain is at the top of the list, and this deck might be just the thing to break my inability to do anything other than play it for full cost to draw a ton of cards, knowing it’s coming back.
Past that, it’s hard to really pull value.  Cards like Expunge and Rapid Decay offer utility, but it’s hard to quantify the real value in the face of Murder or Suffer the Past.  Is the extra card drawn from the cycle ability worth the loss of immediate utility?  Does the fact that Xiahou Dun buys the card back make it better or worse to run one way or the other?
I think the short list right now to examine would be Decree, Scion of Darkness, Twisted Abomination, with Undead Gladiator at the top of the list due to self-recursion.
From Erik:
Pass on Voltron, the general doesn’t lend itself to the build up style.  Coalition Relic is a little too bland in my mind for a mono colored deck, but it does help you hit the BB costs easily, but so do the swamps used for Coffers. I say pass.  Lens is too risky. Pass- it will just get tanked by someone and cost you a card and a land.
So you want to find nonbasic lands? Have you heard of Expedition map? Coffers works well with swamps- Armillary Sphere.
To help get back Xiahou Dun:
Oversold Cemetery– no lost draw step.
Mimic Vat– stick him in it and constantly replay him.
Strands of Night and Crucible of Worlds– no loss of lands.
I’m in full agreement on Voltron versus recursion/sacrifice utility at this point.  Likewise, running mana sources that are either fragile or balanced out over opponents doesn’t seem like a solid way to build advantage.  I think you’re right on in that a card like Armillary Sphere finds you two swamps, while cards like Coalition Relic and Extraplanar Lens just get destroyed. 
I think with the power of Coffers, cards that find specific lands like Map are a must. 
Cemetery is a tough sell for me; I need to be sure that I’m running the creatures to power it out, and from there, I’m nervous that the more this deck loads the ‘yard, the more tempting it is for opponents to target it with graveyard hate.  A card like Dawn of the Dead by comparison, peacock or not, can be run out with a minimal graveyard and not draw much grave hate at all due to diminished targets.  (It’s hard to waste Bojuka Bog on a yard with Xiahou Dun in it and a few other targets, knowing he’s coming right back and you haven’t maximized the scope of the removal.)
Vat, Strands and Crucible…all solid options.  Crucible seems more and more like a must-include. 
From Chad:
I feel the best direction would be focusing in big mana/control. This opens up all stars like army of the damned, curse of the cabal, temporal extortion and drain life effects for finishers. (if you’re feeling mean, helldozer is amazing)
Nirkana is both black and a creature, making it extremely easy to recur…it will draw removal like a lightning rod, although I feel that it is worth it for the effect it brings. Caged sun is far too good to pass up. Gauntlet of power does not seem worth the effort since it benefits all black players and dies a quick death. 
I see no reason not to run crypt of agadeem. It costs some tempo but the upside can be huge and it will always tap for at least one…Everglades is good I have always been a fan of bounce lands for creating an additional virtual land slot.  Lotus vale is a trap all it takes is one player feeling a little vindictive and it’s food for a dust bowl. Not really a fan of lake of the dead.
Liliana I feel is very strong in a deck like this. She can be recurred with you general, grabs a land each turn and is good removal.
For recursion I feel the best options are oversold cemetery and phyrexian reclamation. Both have minimal cost and are very effective. I tried dawn of the dead and it is kind of a peacock. Anything even close to debtors knell gets blown up on site.
I’m feeling a move back toward big mana and a control game too.  The general will be mana hungry to begin with, and I’ve already identified that the draw will bleed life like crazy.  I think Drain Life effects will have to make a return to some extent.
I think it’s important to note the color identity of cards adds to their strength.  Caged Sun is hard to argue with, but looking at Nirkana Revenant next to Gauntlet of Power, the vampire grabs an edge due to Xiahou Dun’s ability to rebuild her post-removal. 
Crypt of Agadeem is a tough sell for the same reason that Oversold cemetery is for me.  I have a feeling that the list will need to come together before I can make either call.  I agree on Everglades, and Lake of the Dead seems like a combo enabler and not much else in retrospect.  Lotus Vale…with Crucible added, it gains a step or two.  Still a potential inclusion.
I need to get my hands on a Liliana
Erik’s back:

I think in mono-black you need to look at the pestilence guys: pestilence demon, crypt rats, and thrashing wumpus. These guys are awesome with mana and pro black. The SoLS really helps make this work. Get the dude, nuke the board, crash into someone get the general back, then go nuts recurring something every turn.

Compelling, although I’d like to figure out a way to make them more valuable.  That might be something like Exquisite Blood. 
From Joe:
What about Nim Deathmantle? I love this guy and it seems like a champ in this deck. Sac Xiahou Dun, pay 4, rinse and repeat. Plus the extra +2/+2 can be significant from time-to-time.
Lake of the Dead, Lotus Vale, Cabal Coffers, and Crypt of Agadeem are all pretty lucrative targets for land-hate, why not run Crucible of Worlds? It interacts especially well with Lake of the Dead and Lotus Vale, returning the lands you sacrificed with them. If you did that then adding in Buried Ruin might be worthwhile because it protects Crucible which protects the Ruin which…etc, etc.
Deathmantle is honestly probably the first card on the list.  The synergy is too strong to pass up.  And I’m now sold on Crucible.  Let’s look to that in later on in here.
We know where the deck is headed; black has the tools to fuel a serious control list, and Xiahou Dun is a perfect general to provide the advantage the deck needs to stay competitive in the face of some of the stronger archetypes out there.
Let’s start by identifying the recursion options.  The beauty of Xiahou Dun as a general is that he’s worded to trigger on sacrifice, so we get the ability no matter where he ends up (unlike, say, Child Of Alara.)  That is part of the appeal for sure, but it’s critical to look at cheaper options.
(A quick disclaimer – I’m all for flavoring to taste later on with singleton options like Animate Dead; I’m sure that will happen to a certain degree.  For now, I want to focus on repeatable options that offer card advantage through repeated use.)
-Dawn of the Dead
-Mimic Vat
-Nim Deathmantle
-Oversold Cemetery
-Phyrexian Reclamation
-Strands of Night
-Sword of Light and Shadow
There’s a lot of appeal here.  Shining examples are going to be the cards that return a creature to hand or play with no help (Reclamation, Deathmantle, Dawn), but there’s potential in other resources such as lands and creatures that can be brought back through other means as well.  The main beauty of recursion in this list is that it’s simply never dead as long as Xiahou Dun remains un-tucked.
Cards that help the cause here– Crucible of Worlds, self-recurring creatures (Bloodghast, Coffin Puppets, Nether Spirit, Nether Traitor, Reassembling Skeleton, Undead Gladiator
A narrow field, but powerful effects.  I have a feeling that Butcher and Pact are going to be central to the operation of the deck.  Jar offers draw and tutoring, which is exactly the kind of extra value this deck wants to see.  These are the kinds of cards that will make the deck really tick; adding a sacrifice to the mix will make things happen with each occurrence, which makes cards further down the list much stronger.
Potential draw and search options that fuel sacrifice.  Again, tons of value with Grave Pact effects.
Some land sacrifice/discard to make Crucible of Worlds (and Grim Discovery) better.
Madness and Transmute options.  I’m shying away from cards that don’t offer a solid effect on their own; if there are some key ingredients later on and discard can be leveraged a bit better, more transmute options could be added.
Made very possible by the category above.
The thing that needs to be kept in the forefront during the creation of this deck is that it will be incredibly easy to get way off target by trying to cram in too man different strategies.  This is a good start towards examining the synergies that can really the deck and create that value I’m after, but I’m sure that I’m missing a bunch of stuff. 
What else works here?  What other potential engines create potential card value? 
I’m drawn to passive abilities.  In the same way that passive mana abilities get around many potential downsides, passive abilities on this end that trigger off of something that we want to do with the deck anyway will be the real bread and butter that makes this thing tick. 
To that end, I’m most drawn to using creature recursion to power out card advantage,  with a second layer of ‘sacrifice/creatures dying matters’ to gain some extra value.  My feeling is that the meat of the deck – the card draw, the finishers – will be what ties this all together.
To that end, what other strategies work here?  What am I overlooking?
Thanks again, everyone.  I know this comes off as a bit of a ‘train of thought’-style posting, but it will all tie together nicely as things start to take more shape, and we can start aggressively cutting and slotting options that really give the deck an identity.