Grisha, Corpse Commander

Double Strike

Whenever you Amass choose a creature type. The army you Amass is a black zombie and the creature of the chosen type, in addition to its other types.
Whenever a non army creature enter the battlefield -Amass 3.
Whenever Grisha Corpse Commander would leave the battlefield you may sacrifice an army instead.

"Come forth my legion, bring all into the march of the
dead!" -Grisha