Vengeful Comets

You conjure a number of miniature comets of ice (up to one per four caster levels) to orbit around you, granting you a circumstance bonus equal to the number of comets on all saving throws against fire effects. Once per round when you are affected by a spell cast by an enemy, you fire one of your comets in retaliation. This is a ranged touch attack that deals 1d6 points of bludgeoning damage and 3d6 points of cold damage + 1 point of cold damage per two caster levels (maximum +10). If the spell you're retaliating against had the fire descriptor, you fire one additional comet.