Revenant orks are a type of revenant that appears to be the undead version of an Ork. Like most revenants, the Revenant ork is much more dangerous than most monsters the same combat level. As Jagex intended, it seems to be almost as difficult as a human player of the same combat level.
Like all revenants, they can recover lost health quickly (1375 per heal), can cure themselves of poison and can quickly react to a player's protection prayers/curses.
Revenant Orks can hit very high with their magic and melee attacks, capable of hitting over 1000+ life points in one hit. Most monsters of the same combat level cannot hit as high. Like all revenants, they have a very large attack range, capable of hitting a player even if the player cannot see them.
The Forinthry Dungeon is a PVP-enabled area, meaning it is entirely possible for other players to attack you whilst fighting the revenants in the dungeon. Do not bring equipment that you are not willing to lose.