Which would you pick?
Robilar's Challenge (PHB2): opponents get +4 attack and damage against you, you get AoO on them for every attack they make, prereqs Combat Reflexes
Karmic Strike (CW, previously OA): opponents get +4 attack against you, you get AoO on them for every hit they make, prereqs Dodge, Combat Expertise
Robilar's Challenge (PHB2): opponents get +4 attack and damage against you, you get AoO on them for every attack they make, prereqs Combat Reflexes
Karmic Strike (CW, previously OA): opponents get +4 attack against you, you get AoO on them for every hit they make, prereqs Dodge, Combat Expertise