Damage to be recieved from an enemy is dealt back to the origin/attacker instead. General Gaskell displays this ability.
His ability is copied and used by Lord Rocambole.
When The First Assassin takes the shape of some one, the damage done to him is reflected back at the enemy instead, where he takes no damage at all. He however can damge the other person.
D seems to counter this by copying his ability to reflect the damage when the assassin goes to cut D's leg, the assassin's leg is cut instead dealing him a critcal blow.