Controlled Immolation( Unearthed Arcana, p. 92)
If you catch on fire, the flames don't hurt you.
Exposure to fireball or delayed blast fireball spell,
If you catch on fire (as described on page 303 of the Dungeon Master's Guide), you take no damage from the flames. A creature striking you with its body or a handheld weapon takes 1d6 points of fire damage. The fire persists on your body for 1d4 rounds. This feat doesn't protect you from other sources of fire dam age, whether magical or not, only from the effects of catching on fire. It also doesn't protect your equipment from the effects of fire.