The special attack is called Armadyl's Judgement, which deals up to 250% damage and uses 50% adrenaline/special attack bar. However, the description has not been updated since the Combat beta's release in January 2014 and this special attack's damage has been tweaked many times since. Test results (critical hit of 5427 at an ability damage of 1460 and no other boosts) suggests the special actually deals up to 372% damage. Under Legacy Mode, the damage is slightly higher to compensate for the larger time interval between attacks.