Forbidden Tomb

When Forbidden Tomb enters the battlefield,
exile all creature cards from all graveyards.
You may cast creature cards exiled with
Forbidden Tomb and you may spend mana as
though it was mana of any color to cast them. Creature spells cast with Forbidden Tomb are
Zombies in addition to their other types.
Discover—{2}{b}, Tap four untapped creatures
you control.