Type: General
Source: Dragon #340
Your knowledge of the supernatural allows you to exploit most attempts to manipulate magical energies.
Prerequisite: Knowledge (arcana) 5 ranks, Spellcraft 5 ranks.
Benefit: You may make an attack of opportunity against an opponent you threaten who dismisses a spell, directs or redirects an active spell, casts a quickened or swift spell, or attempts to turn or rebuke undead. If your attack is successful, your opponent must make a Concentration check (DC 10 + damage dealt) or lose the action that provoked the attack of opportunity.