Lavanica

Original Form: Flying, Trample, Can only be destroyed by combat damage. At the beginning
of each upkeep each creature target player
controls takes 3 damage.
Eruption: At the beginning of your turn this
creature goes into Magma Form: Flying,
Trample. Destroy all artifacts, this creature
recovers all health, and cannot take more than 3
damage per source, revert to original form after
3 turns. Cooldown: 5 turns.