Shrine of the Rat Lord

At the beginning of your upkeep or whenever you
lose life, put a charge counter on Shrine of the
Rat Lord.
Remove three charge counters from Shrine of the
Rat Lord: Create a 1/1 black Rat creature token
with "When this creature enters the battlefield,
each player discards a card."
{2}, {t}, pay 2 life: Target player puts the top four
cards of their library into their graveyard.