Thanatos, God of Death

When Thanatos, God of Death enters the battlefield, you may destroy target creature. If
you do, Thanatos deals 1 damage to you.
{t}: Add {b} to your mana pool.
{2}{t}: Thanatos gains X +1/+1 counters, and
destroys half of X creatures. You lose half of X, rounded up.
"I will not simply bring you to death. I am
Death."