Good lord…you guys are vocal!
From James:

I think for creature recursion you should really try out Death Denied. Use it to return Xiahou Dun and friends to your hand, and then use XD to return Death Denied to your hand. Rinse and Repeat.
Death Denied gives you the ability to create quantifiable value by trading one card for multiples in return.  It’s similar to something like Profane Command, which gives you two abilities for one card.  Both allow a pretty serious synergy loop with Xiahou Dun. 
On the radar for sure.
From Dave:

Vat and Deathmantle are rad. but it’s worth noting that you can’t get them back with XD so the second time you play this deck, they will get blown up asap… translation, Beacon of Unrest (is a must) if these will be essential engines.
Extra value – with your plan to rely on Butcher of Malakir and Grave Pact, passive bonus on dying is good. blood artist and falkenrath noble can make an appearance. mini-nonbo with some of your removal, but if stuff is dying (you’re black control so that seems to be the plan), you’re getting value to be able to draw more cards… already said it in part 3, but just pointing out how redic this line of thinking makes Black MarketAttrition. yawn. but it’s pretty strong. esp with everything mentioned in point 2.
Good points.  Beacon is already a likely top-pick for reanimation utility.  I could attempt extra value from something like Trading Post, which gives me artifact recursion and a sac outlet all in one.  (Plus goats!)  I don’t want to get too off-target, though, so we’ll see how things play out.
Artist and Noble are possibilities, and Black Market is guaranteed to be on the list.  Attrition…tough call.  Repeatable removal bolted to a sac outlet in-color is hard to pass up. 
From Imshan:

It seems like Coffin Queen got overlooked somewhere along the way.  If you’re into big mana and you’re playing a lot of grave pact effects, Black Market is a thing that can go far.  Finally, symmetrical sacrifice effects (Barter in Blood, Innocent Blood) can really get a lot of this to jump off and give your Reassembling Skeletons and Bloodghasts something to do.
Also, should Xiahou only put one counter on Jar of Eyeballs? Unless he hasn’t quite eaten it yet…
Queen is pretty fantastic.  Reanimation and the ability to exile at the same time shouldn’t be overlooked.  Again, it’s going to be tough to fit this all in, so the slots will be tight, but it’s a solid suggestion.  (As is Market again.)
Good call on the sac effects too.  Removal is going to be a fun area to discuss. 
And maybe it’s “Jar of Eyeball” in this case?
Mr. P weighs in:

Prepare to take the same turn over and over again. Fascinating.
To offer proper context, our friend Tyler (who does pop in and post in here from time to time) had a Xiahou Dun deck back before it was cool.  Among other things, it wanted to leverage the ability to play and replay Temporal Extortion repeatedly, until no-one could afford the life payment to prevent the extra turn; at this point, the deck would basically be able to set up endless turns with which to find and abuse win conditions.  Xiahou Dun as a general made it very reliable and inevitable…and kind of painful for the rest of us.
He’s got a good point.
The concern here is re-creating a linear deck that essentially cuts out interactivity and goes for the same game-plan every game.  Needless to say, this is something that will be important to be aware of when creating a final cut of the deck.  There’s a line of demarcation where synergy just becomes ultra-focused strategy, and my hope is to avoid this…or use this as a tool to examine it.
From Erik:

Skullclamp would work great with the sacrifice portions of the deck. It helps draw billions of cards and it is pretty nice to throw extra mana into Reassembling Skeleton and Skullclamp to draw some extra cards.  If you need a back up board control option, Reaper from the Abyss works pretty well with a self-sacrificing general. Decree of Pain: draw tons, kill everything.  Also: is Bridge from Below in the sacrifice section just to prove a point? It will be horrible in multiplayer, actively doesn’t work with Gravepact/ Butcher of Malakir, and when it does work- it will draw attention. The card is a big name due to dredge decks, and no one will think you aren’t running combo with it.
‘Clamp is possible.  Realistically, I need to branch out from draw that also annihilates my life total, so enough recursion might make this a good include. 
Reaper is going to make the cut.  Morbid is a great fit for the deck.
Bridge was added to the sacrifice section because realistically it creates value with Xiahou Dun by providing more tokens to sacrifice for other things.  It’s honestly probably not worth the slot in this format, and you’re correct in that it will falsely key people in to a combo dredge theme; more grave hate is not what I want.
Speaking of…
Mr. P:

You should play Bridge from Below just so you can hard cast it on turn three and win immediately.
Point taken…Bridge is out.  🙂

I wanted to get to tutors and draw as soon as I could, because I feel like this is going to be a great place to tune the balance of the deck.  Obviously, it’s possible to jam the deck full of black tutors and always be able to set up whatever engine I want to whenever I want, but going back to what was said above, I don’t want to create a boring one-trick pony here.  A deck can be potent and synergistic and still be fun and interesting to play if the build is managed correctly.
The trick here is to apply what we’ve identified as core strategies, and work to figure out what the balance is. 
This is also the reason I like to go heavy on card draw.  The reason card advantage is so crucial in Magic is that it opens up many avenues and strategies to a player for any given board state.  Tutors get you specific answers to specific threats, or find you specific elements to further your current plan of attack, but they rarely create real card advantage; you’re usually looking at a one-to-one trade-off.  Draw gives you the option to keep fueling mana, creatures, and other components at what is usually a multiple-to-one ratio.  This is important, because drawing a single card a turn will ultimately be a game of diminishing returns.
Furthermore (and maybe most importantly when relating to the spirit of the format), draw keeps things randomized.  It’s far-more fun and exciting to rip a critical piece of removal off the top at just the right moment than it is to Demonic Tutor up Damnation or Exsanguinate.  A little tutoring to get on the right track seems fine, but you can’t have enough draw.
The Tutors:

-Demonic Tutor
These are the “raw” tutors I’m considering.  There are other options (Grim Tutor, Imperial Seal) that just fill the same role for a large price-tag, and to be honest, not all of these are even coming close to making the final list anyway.
Since we’re working on recursion, it doesn’t hurt to consider options that go straight to the graveyard.
Transmute and Transfigure options.  Historically, I steer clear of cards like this that provide a mediocre body or effect (in most cases) and a limited other effect (tutor, draw, whatever.), but in this case, the appeal is in the synergy with the general, so I’m willing to give things a second chance if they end up being the right fit.
Demonic Tutor with legs.  And wings.
Honestly, I’m not particularly invested in this section.  The final tutor slots will be minimal, but will probably focus on the best examples possible (Demonic), or the most synergistic (Collusion, Dreams.) 
The Draw:

Artifact options.  It needs to be very solid in this category to get the nod over black cards that Xiahou Dun can recur.
Honestly, black is as heavy as blue is with draw – it just hurts a bit more.  Everything is a tradeoff; you’re giving up life or creatures/permanents.  It probably doesn’t need to be said, but what comes out of this section will directly drive how we manage life-gain.  My initial estimate is leaning towards more, not less.
I am liking the goods in here that provide sacrifice outlets, however.  Infernal Tribute?  How has this gone under my radar for so long?
Again, draw that brings a warm body to the party.  I’m particularly looking forward to seeing how well Disciple will work in here; with enough creature support and a sacrifice outlet to get him in the ‘yard for Xiahou Dun, he’s a serious draw engine on his own.
-Decree of Pain
Dual role-players, as with the creatures above, gain value for the deck.  Decree is an all-star to begin with, and Dregs can play a similar role in a big-mana build.  I’m looking to expand options like this in the long run.
Cyclers in various card types.  Some of these are showing up multiple times now in our lists (such as Undead Gladiator and Twisted Abomination), which is a flag for me that I’m seeing value in cards that play multiple roles.  Often when I create a deck I use this exact process, looking at cards for each category and listing things out in an Excel spreadsheet.  When I start to see the same name multiple times across different categories, I know I’m looking in the right direction both card-wise and strategy-wise.   

There isn’t a huge amount of detail in this section, and for that I apologize.  I really feel like draw and tutors are means to an end, and rarely are very interesting, so it’s hard to put a solid qualifier for each card.  For me, it’s more important to define what needs will have to be met by these two categories and what the likely inclusion ratios will be, and then identify the options.  I’ll fill in the meat of the deck, and backfill from these sections with the best options when things start to take shape to make things tick.
So, as usual – What else is out there to look at?  What did I miss?  Are there other mechanics or angles that would work well with how this deck is shaping up?
Hit the “Comments” section and let me know what you’re thinking.
Up next – a look at removal, and the core of the deck will begin to take shape.