Messmer, Banished Scion

Whenever Messmer deals combat damage to an opponent, destroy up to one target permanent that
player controls.

Abyssal Serpent — {b}{r}, Sacrifice a permanent: If
Messmer isn't a Snake, put two +1/+1 counters on
it and it becomes a Snake with trample in addition
to its other types and abilities. Otherwise, Messmer
deals 4 damage to any target. (Activate only if this creature was dealt damage this turn.)