Lord Skreech Verminking

Cascade
Ratstorm (When you cast this spell, create a 1/1
black rat creature token for each spell cast this turn.)
{b}{b}{b}, {t}, Sacrifice 13 rats: For each opponent,
exile the top 13 cards of that player's library.
That player loses life equal to the total mana
value of cards exiled from their library this way.
If a player's total is zero, you lose the
game.