[Reserve]

Your reservoir of magic allows you to breathe normally even underwater.

Prerequisite: Ability to cast 3rd-level spells

Benefit: As long as you have a water spell of 3rd level or higher available to cast, you can breathe normally in both air and water. This supernatural quality requires no activation. As a secondary benefit, you gain a +1 competence bonus to your caster level when casting water spells.

Rulebook: Complete Mage (p. 39)

Edition: Supplementals (3.5)