Removal
Dreadbore : 2 drop standard removal
Hero's Downfall : the instant speed Dreadbore . Killing planeswalkers and the toughest of creatures in the opponent's turn. also takes care of master of waves
Mizzium Mortars : one of the few things that hits Blood Baron of Vizkopa
Warleader's Helix : has saved my life more than a few times with the lifegain, and 4 damage is usually enough to kill most creatures for the early part of the game. After that, I can still target my opponent, or opposing planeswalkers.
Anger of the Gods : wrecks agro
Magma Jet : scry 2, generally don't have anything happening that early anyways and it can get rid of those little pests before they become problem
Creatures
Boros Reckoner : Magicow is here to even the playing field, and he does everything he's supposed to do: stall. He hits the field and immediately grabs the opponent's undivided attention, helping me to set up my next few turns.
Sin Collector : hits control, trades with aggro creatures, a little boardpresence in the early game
High Priest of Penance : just used to stall just like the reckoner
Desecration Demon : one of the most difficult creatures to deal with, must have hard removal for him. Burn spells don't do the trick, unless you waste multiple on him.
Stormbreath Dragon : I don'y know why, but he fits in really well with this deck. plus it's hasty so that always helps
Blood Baron of Vizkopa : Dodges a ton of removal, gains life, deals damage and is very difficult to block
Obzedat, Ghost Council : Dodges wraths, gains me life every turn while bleeding the opponent out, and is a pretty decent body to attack with every turn. plus if you bring him back with the whip (happens more often than you'd think) you get him to stay by exiling him.
Aurelia, the Warleader : She finishes the match almost every time. An additional combat phase is too much for almost any opponent to handle, and if Desecration Demon is on the field, there's nothing you can do. It takes instant speed removal to avoid this instant death. And it must be done before she is declared as an attacker, or it's too late
stabilizers
Whip of Erebos : If someone manages to kill my creatures, they come back with a vengeance. The lifegain is a plus, and a very strong one at that.
Rakdos's Return : if it hits around turn 6-7, it is guaranteed to ruin the rest of the match for the opponent.
Read the Bones : with so much going on in this deck, having a way to sift through what I don't want at the moment is just plain lovely