Ruby, Lady of Blood

Lifelink
At the beginning of your upkeep, if a player owns
five or more cards with a stone counter on them,
you win the game. Otherwise, you gain 2 life.
Whenever a creature an opponent controls dies,
if it was dealt damage this turn by a creature you
control with lifelink, exile it with a stone counter
on it instead of putting it into its owner's
graveyard.