Choose an element (air, earth, fire, or water). You cast spells with that descriptor more effectively than normal.
Prerequisite: Knowledge (the planes) 2 ranks.
Benefit: You cast spells with the chosen descriptor at +1 caster level.
Special: You can gain this feat multiple times. Its effects do not stack. Each time you take this feat, it applies to a new element.
Source: Planar Handbook, page 39.