Wizen, Gray Necromancer

When Wizen, Grey Necromancer enters the battlefield under your control, shuffle all Zombie Creature cards from your graveyard into your library.
Zombie Creature spells you cast cost {1} less for each Zombie you control.
{b}: Create a 2/2 Black Zombie token. Use this ability only when another nontoken Creature dies.
{b}{b}, {t}: Search your library for a Zombie Creature card, reveal it, and put it in your hand. Then shuffle your library.