Enduring Titan

Trample, hexproof from creatures
Whenever Enduring Titan enters the battlefield
or attacks, you may sacrifice another creature. If
you do, put a number of +1/+1 counters on
Enduring Titan equal to that creature's toughness.
At the beginning of each end step, you may pay {x}{x} and remove X +1/+1 counters from
Enduring Titan. If you do, you gain X life and
draw X cards.