SHADOW-STRIKE - Can be obtained from Clarissa of the Shadows inside Forgotten Woods by Reapers around level 800.

Shadow-strike is a passive skill once acquired. When you trigger an attack in combat it will execute in the first round providing additional damage.

You must be stealthed to gain this effect and know the Shadow-strike skill.

Also once executed your health will take a 20% penalty as the efforts of the blow take its toll on you. However the damage you deal should exceed the damage taken.