You can modify a spell that uses one type of energy to use another type of energy.
Prerequisite: Knowledge (the planes) 1 rank.
Benefit: Choose one type of energy: acid, cold, electricity, fire, or sonic. You can modify a spell with an energy designator to use your chosen type of energy instead. An exchanged spell works normally in all respects except the type of damage dealt. For example, an exchanged (cold) fireball behaves exactly the same way a normal fireball would but deals cold damage instead of fire damage.
If you cast a spell that already has your selected descriptor as an exchanged spell, the spell gains an additional effect based on that descriptor, as detailed below.
Cold: Target must make a Fortitude save or be slowed for 1 round.
An exchanged spell uses up a spell slot one levels higher than the spell’s actual level.
Special: You can gain this feat multiple times. Each time it applies to a different type of energy.