Energy Aegis

(Player's Handbook II, DnD 3.5)

Abjuration

Level: ; Cleric 3; Duskblade 3; Sorcerer/Wizard 3
Components: V
Casting Time: 1 immediate action
Range: Close (25 ft. + 5 ft./2 levels)
Target: One creature
Duration: 1 round
Saving Throw: Will negates (harmless)
Spell Resistance: Yes (harmless)

A nigh-invisible ripple of magical energy courses through the creature touched, granting it resistance against one type of energy specified by you during the casting the spell.
When you cast energy aegis, specify an energy type (acid, cold, electricity, fire, or sonic).
Against the next attack using this energy type that targets the subject, it gains resistance 20.