After a relatively brief incantation, enchants the current weapon with a dark-element enchantment. While the enchantment is active, attacks create an extra tongue of dark energy, increasing the knight's effective attack range and adding extra hits and damage.
Any sword/mace skills used with Abyssal Anguish will create shockwaves of darkness with good stun property and moderate range. This also works with the heavy melee and its core skill, as well as the light attack's core skills, the latter which will produce a total of 4 shockwaves.
This is one of the most useful and powerful Mystic Knight skill. Using it with the staff's heavy attack almost makes it like a staff-sword.
Causes dark-element damage as well as physical. Using it on enemies weak to darkness, such as The Dragon, proved to be extremely effective.