Skullgar, Bone Knight

Trample
Whenever Skullgar, Bone Knight deals combat
damage to a player, put two +1/+1 counters on it.
You may remove three +1/+1 counters from Skullgar, Bone Knight. If you do, untap Skullgar,
Bone Knight. After this combat phase, there is an additional combat phase.

Ancient, temporal hatred channeled by Za'Koth into a multitude of desolate bones.