Improved Combat Casting
( Complete Arcane, p. 192)[Epic]
You heighten your ability to cast spells while threatened without fear of being attacked.
Prerequisite
Combat Casting (PH) , Concentration 25 ranks,
Benefit
You get a bonus equal to 1/2 your caster level on Concentration checks made to cast a spell or use a spell-like ability while on the defensive or while you are grappling or pinned.