Lucretia, The Strongwilled

This cards enters the battlefield with {x} +1/+1 counters on it.
Whenever a creature enters or leaves the
battlefield, put {x} +1/+1 counters on Lucretia
equal to the converted mana cost of that creature.
{t}: Remove {x} +1/+1 counters from Lucretia
and then draw {x} cards and gain five life.