Vulvix, Sadistic Tormentor

Whenever a player sacrifices a creature, look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard. This ability triggers only once each turn.
Delirium - At the beginning of each opponent's end step,
if there are four or more card types among cards in your graveyard, you may choose two different creatures that player controls. That player chooses one of them, then sacrifices the other.

“Sometimes the whitest of fur conceals the darkest of heart