Evasion (3.5e Feat)
From D&D Wiki
You are adept at avoiding area attacks
Prerequisite: Dex 15, Lightning Reflexes
Benefit: You can avoid even magical and unusual attacks with great agility. If you make a successful Reflex saving throw against an attack that normally deals half damage on a successful save, you instead take no damage. Evasion can be used only if you are wearing light armor or no armor. A helpless character does not gain the benefit of evasion.
Normal: With a successful Reflex saving throw against an area attack, you take half damage.
Special: If you already have Evasion as a class feature, you take half damage on a failed saving throw.