When I thought of the implications of this, my jaw just dropped. This will need some polishing to it, most certainly, but I think this could be an absolutely KILLER idea.
So, the meat of the deck - Heartless Summoning + Mikaeus, the Unhallowed - cheaper spells, the +1/-1 cancel out, and lets give stuff undying!
Solemn Simulacrum - make early abusive use of the heartless summoning and then the undying
Sangromancer - mostly just a nice creature for heartless summoning
Rune-Scarred Demon to tutor and have a nice flyer.
Hex Parasite because abusing the undying mechanic can only get better, right??
Skithiryx, the Blight Dragon because he just belongs in any heartless deck.
Sheoldred, Whispering One mmmmm, more creature return. Yay.
Grave Titan because come into play effects with undying is just uber fun.
Wurmcoil Engine aka Wurmcoil Titan is just giddy fun to have with undying.
After that, just some removal. Hopefully there will be enough beatdown going on that removal is not dire.
Biggest "crutch" I see to this deck is the heartless summoning. Without it, it slows the deck down some, hopefully not too much. Turn 4 seems to be when most decks stabilize/gather momentum - I would hope to either have Heartless Summoning out with a Solemn Simulacrum to help mana/card acceleration.
I really feel like
Myr Superion
is a huge neglect to leave out of the deck, Might remove a one-of of a couple things to get 2 of him a spot.
Sideboard
Ratchet Bomb - black's only ability to handle enchantments and some annoying forms of hexproof
Black Sun's Zenith - board wipe if need-be
Dismember - super quick removal if necessary
Gravepurge
because getting creatures back to do it again is FUN!
Phyrexian Crusader - vs Red/White, super fun, but sucky to have with heartless because of smaller size - still thinking on this one.
Tribute to Hunger
- another answer to hexproof, not a fan though because I always seem to get it when they have a puny worthless something to sacrifice instead.
