Energy Fusion Feat 10
Source Pathfinder Advanced Player's Guide
You fuse two spells together, combining their energy types.
If the next action you use is to Cast a Spell that deals acid, cold, electricity, fire, or sonic damage, select a non-cantrip spell in your spell repertoire that deals a different type of energy damage from that list, and expend an additional spell slot of the same level as this secondary spell. The spell you cast deals additional damage equal to the level of the secondary spell slot expended.
The spell's total damage is divided evenly between the energy type of the spell you cast and the energy type of the secondary spell.
Traits
Anything that doesn't list another rarity trait (uncommon, rare, or unique) automatically has the common trait. This rarity indicates that an ability, item, or spell is available to all players who meet the prerequisites for it. A creature of this rarity is generally known and can be summoned with the appropriate summon spell.
ConcentrateAn action with this trait requires a degree of mental concentration and discipline.
MetamagicActions with the metamagic trait, usually from metamagic feats, tweak the properties of your spells. You must use a metamagic action directly before Casting the Spell you want to alter. If you use any action (including free actions and reactions) other than Cast a Spell directly after, you waste the benefits of the metamagic action. Any additional effects added by a metamagic action are part of the spell's effect, not of the metamagic action itself.
SorcererThis indicates abilities from the sorcerer class.