Windlash (Aematha)

When you crit with an attack with Aematha, you may take a 5 foot step and make an attack against a different opponent within range as a free action, using the butt of the weapon. (This attack does 1d8 bludgeoning damage.)
This does not invoke an attack of opportunity, does not deal bonus damage from Followthrough, and does not effect the stacks in any way.