Utalak, Ursine Rage

Whenever you play a green creature spell, put a +1/+1 counter on Utalak, Ursine Rage.
{g}{g}{t}: Remove 2 +1/+1 counters from Utalak, Ursine Rage. Create a 2/2 green bear creature token.
{x}{g}: Sacrifice any number of creatures you control. Utalak, Ursine Rage gets +2/+0 for each creature sacrificed this way and trample.