Volcano Domain

Revered as the chimneys of deific forges, the prisons of terrible entities, or sometimes as gods themselves, volcanoes attract faithful and powerful followers. Volcano clerics foster fissures in the earth to bring up the fire from beneath, whether for good or ill.

Ash, magma, and poisonous gasses are also among the gifts they receive.

Tephra Trap (Sp)

You can create a Tephra Trap, a hidden patch of ground where a temporary rift extends into the earth, prepared to eject a small explosion on any who steps upon it. The explosion deals 1d8 damage, +1 damage for every two levels of cleric you possess. The Tephra Trap takes 1 minute to create, and the DC to make a Reflex save for half damage, locate it, and disarm it is 10 + 1/2 your cleric level + your Wisdom modifier. The Tephra Trap lasts for one hour per cleric level.

Caldera Calling (Su)

Starting at 8th level, you can temporarily conjure calderas that lead straight to the world's core (or another sufficiently flammable locale of your deity's choosing). Treat the caldera as a cylinder with a 10-foot radius that deals 3d6 fire damage and 1d6 bludgeoning damage. One caldera may be created per four cleric levels, and they may be created up to twenty feet away per cleric level. Using this ability in a region with strong volcanic activity upgrades the damage from 4d6 to 4d10. The saving throw to halve the damage is 10 + 1/2 your cleric level + your Wisdom modifier.