Asareth, Endless

Asareth enters the battlefield with a +1/+1
counter on it for each {b} you spent to cast it.
When Asareth leaves the battlefield, you may
exile it with an age counter for each +1/+1
counter that was on it. You may cast Asareth
from exile as long as you pay an additional {b} for each age counter on it.
{t}, remove X +1/+1 counters from Asareth: Each opponent loses X life and you gain X life.