Akromas Will is probably the best finisher in the entire deck, but you might also use it to protect your creatures from a board wipe or surprise someone who thinks that their board can punch through your side of the battlefield
Morbid At the beginning of your end step, if a creature died this turn, populate
It combos off on its own with a Blood Artist, Butcher Ghoul, and a card that makes a token when a creature dies, including Nest of Scarabs, Pawn of Ulamog, and Sifter of Skulls
If your infect deck is doing its thing, you wont need more than two hits from this black skeleton dragon to end the game, and it gets better with power pumping effects or double strike (Fireshrieker)
As soon as a dungeon has been completed, a creature from your own graveyard may be put back into play