Hey i like your deck its pretty similar to mine, Sacrifice and reanimate. A few cards you might adding could be Vish Kal, Blood Arbiter , and Retribution of the Ancients . They both combo perfectly with Mikaeus, the Unhallowed . You can sacrifice any ETB creature to Phyrexian Altar for one back mana,use that black mana to take off Mikaeus, the Unhallowed 's undying trigger with Retribution of the Ancients . I just thought of this combo recently and i am hoping to acquire it soon.

@jaeger_Konig: Thanks, but I try to avoid going infinite. I added Mikaeus because undying and persist work well with what my deck does. Unfortunately, Mikaeus is an infinite combo machine. I try not to go for him until I feel like ending the game. Thanks, though.