Azcababs violent rebuke

When the caster or one of his spells is the target of a spell then he may choose to use a reaction to launch a violent counter strike against the caster. A lance of emerald light bursts forth from the user in the direction of the attacker, passing through cover and striking the target for 2d8 radiant damage. Any targets between the two casters must make a dex save or take 1d8 radiant damage.

At higher levels: For each level above 2nd used to cast the spell, an additional 1d8+1 damage is added to the attack against the main recipient.