needs more Lord of the Undead

Mimic Vat + Fleshbag Marauder let's you control the board through sacrifice. Grimoire of the Dead seems like a must have for this. Eldrazi Conscription makes your opponents sac more. Butcher of Malakir and Lim-Dul the Necromancer feel really slow when you compare them to Grave Betrayal and Grave Pact . There's a really good Thraximundar deck called Thraximundar's Decree that I based my deck off of.

if you really want to be a dickbag, run Grave Pact and a whole bunch of Shadowborn Apostle . since you're running zombie tribal, you can't really tutor up demons (unless there's a zombie demon that I don't know about) but you can just sac them, search and fail to find, then wipe your opponents' boards by multiple Pact triggers.