Yawgmoth, Thran Physician Yawgmoth, Thran Physician offers the mono-black sacrifice deck otherworldly card draw, provided they dont ask what happened to their livestock and children
Phyrexian Obliterator is the better of the two, but also has to go toe to toe with Sheoldred, the Apocalypse, one of the best Black 4-drops of all time, so prospects ain't looking good
(In the English version he quits the Obelisk Blue dorm stating that Blue wasn't his color and he left Blue to protect Jaden)
You dont have to repeat this play pattern many times for the game to just be over, and if you miss a turn and have to tap a potential attacker, you are still clocking your opponent very well
Gate Deeg
With access to black, you can play more of a bleeder deck with lifegain synergies