Mepher, Prince of the Realm

Flying, Deathtouch
Mepher, Prince of the Realm is indestructible as
long as you control 4 or more Mephers
Whenever another creature you don't control is
put in a graveyard or is exiled, put it on the battlefield under your control instead. It gains an emblem that does "this creature is a Black
Mepher in addition to its other colors and types.
When this creature dies, exile it"