You are adept at spellcasting when threatened or distracted.
Benefit: You get a +4 bonus on concentration checks made to cast a spell or use a spell-like ability when casting on the defensive or while grappled.
Endzeitgeist Says: This is a great feat whenever you want to cast within the range of foes - be that melee or ranged. Casting defensively increases the DC by +5, meaning that this feat (almost) negates the penalty!
The Sage of Chandegar says: This feat is a must have for a casting class characters who will find themselves within the reach of an enemy's blade. Remember to state that you are "casting on the defensive" when you are using this ability. Also, do not forget that this feat works for "spell-like abilities" as well.