Nissa, Voice of Death

When Nissa, Voice of Death enters the battlefield sacrifice her unless you control a mono black planeswalker.
{g}{g}{g} Exile Nissa, Voice of Death: Forests you control become 2/2 black and green plant zombies with haste until the end of turn. They are still lands.
"I never expected the elf to die. Oh well she's mine
now!"
-Liliana Vess