Extensive preparation is required here. Since the run is no-regen, it is necessary to maximise your max hp/sp before entering the area, and to regen to max before entering the area. The boss mob has to be solo-ed, therefore to make it go quicker, I would recommend mixing 30-50 HE before entering the area. Lesser demons can be spooked, so psionics will be useful in this run.
The prelude to the Demon Lord of Cruelty
Basically, the run consists of killing all the demons in the area. Once that is done, the path to the Demon Lord of Cruelty is opened. Most of the area is no-form. I would recommend the form to split into either 3 forms of 3, or 2 forms to kill the mobs in the area. Ideally, there should be 2 forms of 4-5 players at the start before going down to groups of 2-3s as the mobs thin out and become harder to locate. The tanks should have max ar and do high damage. Always make sure that there's someone out of combat to heal you when you enter combat with a mob since it is not possible to get back to the area after death.
Sp-conservation is key here. I recommend only casting cure light on the tanks through this entire area. Druid tanks should use druid heal as it is more efficient. Agrippa rings work in this area and should be used.
Take note: Calming causes the mobs to go crazy, and is not advised.
Once all the mobs are killed, a north exit from the start room opens, leading to the Demon Lord of Cruelty. The boss mob has to be solo-ed, so ideally get a valkyrie tank with high damage to solo the boss. The other players will heal the tank out of combat, while the tank lobs HE at the boss. The boss takes a while to fight, but it shouldn't be too tough