My friends and I have started playing Conan Exiles, visiting The Dregs several times now and each time we have gone the Abysmal Remnant boss at the end of the dungeon can very easily be killed by just shooting it to death with arrows without it attacking anyone or moving a single time.
We are playing on an official pvp server through Steam and have never used any mods.
It just sits there not moving or attacking, much like this screenshot from the wiki: