Spellcasting Harrier
From Compendium of Worldly Lore
Needs review
Source: Draconomicon
Description: Spellcasters you threaten find it difficult to cast defensively.
Prerequisites: Epic Level, Combat Expertise
Any spellcaster you threaten in melee provokes an attack of opportunity if he or she tries to cast defensively. You get a +4 bonus on this attack roll.