Empower Spell

You can empower the spell of an allied creature you can see within range. Once the spell is cast you empower the casting of the targeted creature by the level expended to cast empower spell. You can empower a allies spell up to a 9th level spell but no farther.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the empowered spell is strengthened by the level of spell that is used in the casting of empowered spell.