Requirements: Stealth 1
Applies whenever you attack from the Rear in Optimal Reach. No need to declare.
Use [Stealth + Finesse] instead of [Combat + Vigor] to determine your Weapon Skill for the attack.
Add Stealth to the damage roll.
Even if your opponent changes Facing after you declare your attack, the attack counts as from his Rear regardless.
Can be combined with Stealth Kill if meeting all requirements.