Evocation [Electricity]
Level: Sorcerer 5, Wizard 5
Components: V, S
Casting Time: 1 immediate action
Range: 5 ft.
Target: One creature
Duration: Instantaneous
Saving Throw: Fortitude partial
Spell Resistance: Yes
You can cast this spell only when another creature has just dealt hit point damage to you with a melee attack. When you cast electric vengeance, a blast of lightning arcs from your body into the subject’s; the arc deals 5d8 points of electricity damage +1 point per caster level (maximum +15), and the target of the spell must succeed on a Fortitude save or be dazed until the end of your next turn.
Source: Player’s Handbook II, page 111.