Guardian of Gelbane

Whenever you cast a spell, lose 1 Life.
Whenever an opponent casts a spell or plays a
land, put a +1/+1 counter on Guardian of
Gelbane. It has hexproof until end of turn.
Remove two counters from Guardian of Gelbane:
deal 2 damage to any one target.
"All it knows is its duty, but that's enough."
—Melthane, Build-Master