Dark Cultists are human mages who spawn with Berserkers. Cultists are very weak, but they can shoot fireball projectiles and summon powerful Dark Demons, so it's wise to bypass the hulking Berserkers to kill the Cultists as quickly as possible.
Cultists can be recognized from Dark Vessels by their lack of a staff. Vessels have a long staff which curls at the end, on which they lean while summoning up the demons by which they are possessed.
The backstory behind the cultists is described in an entry on the Official Site. An excerpt:
- That was when I first saw them, the dark cultists, arrayed in a circle. Their torches lit the macabre proceedings in a pallid light that danced over their garish rune-covered robes. I had heard tales of these hooded cultists and their depraved rituals, and I must admit to some curiosity upon seeing them. As their chanting droned on, I thought to make my escape lest they see me, but my attention was riveted by a pale, vacant-eyed supplicant being led forward. I do not know if he was of limited mental capacity, lost in religious mania, or simply drugged, but he was definitely not sound of mind as he knelt in the center of the thrumming circle.The chanting stilled as the leader, face shadowed by a heavily gilded hood, stepped forward and began to intone a ritual in some indecipherable tongue. A large, thickly muscled and leather-masked cultist draped a black, eyeless hood over the victim's head before pulling a foot-long spike from his sash. My mind searched for any possible use for this cursed nail when I noticed the immense stygian hammer grasped in his other hand. With one swift motion, he raised it above his head and drove the spike into the supplicant's back with fierce intensity. I almost screamed... but the victim made no sound. As another spike was readied, I knew I could watch no more. I trembled with the thought of those nails being driven into me should I be caught. I averted my gaze as I heard the revolting squish of another spike sunk into willing flesh. My eyes fell on the robe of the lead cultist. The intricate runes woven into his robe undulated and swirled in sickening movement. As I watched, horrified, I could feel my sanity crumbling away. I began to back away from the wicked tableau, forcing myself to move slowly while my mind screamed for me to flee with abandon. When I could contain myself no longer, I broke into a full run, not caring what sound I made. I ran until I collapsed. And then, as soon as I was able, I staggered to my feet and ran some more.