Sevich, Master Necromant

Whenever you cast a zombie creature spell,
create a 1/1 black zombie creature token.
Zombie creature cards in your graveyard have
unearth equal to their converted mana cost.
Whenever you cast a creature spell, you may exile
any number of zombies you control to reduce
the mana cost by {1} for each zombie exiled this
way. If you do, that creature enters the battlefield
as a zombie in addition to its other types.