Elemental Body IV (Fire)

You become a huge fire elemental. You gain a +6 size bonus to your Dexterity, a +4 size bonus to your Constitution, a +4 form natural armor bonus to AC, resist fire 20, and vulnerability to cold. You also gain two 2d6 slam attacks and the burn ability. You are immune to critical hits and sneak attacks while in elemental form and gain DR 5/—. Your movement speed is increased by 20 feet. Burn: A fire elemental deals 2d6 fire damage in addition to damage dealt on a successful hit in melee. Those affected by the burn ability must also succeed at a Reflex save or catch fire, taking 2d6 damage each round for an additional 1d4 rounds. Creatures that hit a burning creature with natural weapons or unarmed attacks take fire damage as though hit by the burning creature and must succeed at a Reflex save to avoid catching fire.