Energy Substitution

 
Prerequisite(s): Knowledge (Arcana) 5+ ranks, Ability to cast at least one spell of each energy type (Acid, Cold, Electrical, Fire), Any other Metamagic feat (See main index)
 
Benefit: Choose one energy type, you can modify any spell that has an energy descriptor to the chosen energy type. A spell so modified works normally in every way except for the type of damage dealt. A spell modified with this ability can be further modified by other metamagic feats. This feat can be taken multiple times, each time it applies to a different energy type.
 
Source: Complete Arcane