Magma Mephit

(from Planescape: Monstrous Compendium Appendix I - 1994):

Magma mephits, or lava mephits, are the least intelligent of all mephits and hence the brunt of fire mephit jokes. They are sensitive to these insults and anger easily when offended, but otherwise they are passive and less temperamental than other mephits. They generate extreme heat that can be felt 30’ away.

Combat: Magma mephit claws are small and soft, causing only 1 hp damage when they hit, but each hit inflicts an additional 1d8 heat damage and automatically melts or burns most nonmagical materials. The rate of destruction varies from three rounds (melting plate armor) to one hour (burning through an inch of wood).

Their breath weapon, usable once every three rounds, is a blob of lava that automatically hits one target within 10’ (1d6 damage). A magma mephit can use this weapon eight times, then must recharge for one hour in a lava pool. Mephits in lava regenerate 2 hp per round.

Magma mephits can shapechange into a pool of lava 3’ in diameter and six inches deep. This maneuver does not recharge their breath weapon. They take damage normally in pool form.

Once per hour a magma mephit can attempt to gate in 1-2 other mephits of fire, magma, smoke, or steam. If two arrive they are the same type.

Water in large quantities (a barrel or more) causes the magma mephit to harden, halving its movement. However, this releases large quantities of sulfurous steam, necessitating a save vs. poison for any creatures within 10’. Failure causes dizziness and nausea for two rounds, and the victim takes -2 on attack rolls.

(From 3.5e Monster Manual I - 2003):

This winged creature looks like a brutish, miniature human made of molten stone and glowing lava. 

Magma mephits come from the Elemental Plane of Fire. Magma mephits are slow-witted and brutish. Each one is about 4 feet tall and weighs about 60 pounds. 

Magma mephits speak Common and Ignan. 

Combat:

Breath Weapon (Su): 10-foot cone of magma, damage 1d4 fire, Reflex DC 12 half. Living creatures that fail their saves are tormented by burned skin and seared eyes unless they have immunity to fire or are otherwise protected. This effect imposes a –4 penalty to AC and a –2 penalty on attack rolls for 3 rounds. The save DC is Constitution-based and includes a +1 racial bonus. 

Spell-Like Abilities: Once per hour, a magma mephit can use shapechange to take the form of a pool of lava 3 feet in diameter and 6 inches deep. The mephit’s damage reduction improves to 20/magic when in this form. The mephit can’t attack while in lava form but can use other spell-like abilities. It can move at a speed of 10 feet, but it can’t run. In this form the mephit can pass through small holes or narrow openings, even mere cracks. The pool’s touch ignites flammable materials such as paper, straw, or dry wood. 

Once per day a magma mephit can use pyrotechnics (DC 14). It can use itself as the fire source without harm. Caster level 6th. The save DC is Charisma-based. 

Fast Healing (Ex): A magma mephit heals only if it is touching magma, lava, or a flame at least as large as a torch.