The Necromaster

You may choose not to untap The Necromaster during your untap step
At the beginning of each end step, you may put a corpse counter on target creature in a graveyard whose turn it is. (creatures with corpse counters are zombies in addition to their other types)
{t}: Exile target creature from a graveyard or the battlefield with a corpse counter on it. When you do, each zombie you control becomes a copy of the exiled creature until the Necromaster becomes untapped