Izu, Keeper of the Deadgate

Whenever a creature card is put into an
opponent's graveyard from anywhere other than
the battlefield, that player may pay 1 life and
exile that card from their graveyard. If they
don't, you may draw a card.
{u}{b}{r}, {t}, Discard a card: Each opponent mills
a number of cards equal to the discarded card's
mana value. (To mill a card, a player puts the top
card of their library into their graveyard.)