Burning AmplificationSource Magic Tactics Toolbox pg. 8
You can expend some of the energy of your fire spells to make the flames linger long enough to cause your opponents to catch ablaze.
Benefit: Whenever you cast a spell with the fire descriptor, you can take a –1 penalty on the spells’ attack rolls and reduce the spell’s saving throw DC by 1 to cause any target that is dealt fire damage to catch on fire (Pathfinder RPG Core Rulebook 444). The targets do not take burning damage for catching on fire until their next turn, and each target can attempt a Reflex saving throw to put out the fire before being damaged each round. Rather than the normal DC 15 Reflex saving throw to put the fire out, the target must succeed at a Reflex saving throw with a DC equal 10 + the spell’s level + the modifier of your spellcasting ability score). You must choose to use this feat before making an attack roll or before your targets attempt their saving throws. This feat has no effect on spells that neither allow a saving throw nor require an attack roll.