Loreleia, Bladewind Stalker

When Loreleia, Bladewind Stalker enters the
battlefield, put a mark counter on up to three
target creatures.
Whenever a creature dies, if it had a mark
counter on it, it's controler loses 3 life and you
gain 3 life.
{b}{g}, {t}: Loreleia deals damage equal to her
power to target creature.