These are probably one of the hardest hitting creatures in the game and are the heavy fighters of the Shadow Army. They can lay down the hammer on spell casters and warriors alike, especially with Knockdowns and Deep Wound. These creatures will knock down their target whenever they land a critical hit, whether they use a skill or not.
Blinding or weakening Abyssals can greatly reduce their damage output. Overall, conditions are effective because these creatures do not possess any condition removal skills nor are they ever around any other mobs that do.
It is highly advisable for casters to avoid direct confrontation with these enemies. Abyssals are capable of dishing out great damage, knockdowns and brutal interrupts. They can take out a caster in three hits, during which the victim will not have a chance to cast anything or run far.
Abyssals have been noted to attack other creatures in the Fissure, particularly the Shadow Army. Whether this is a bug or not has yet to be confirmed.