The Fall of Shanti

Well, I don't know, I'm just playing through the campaigns on recruit difficulty... I just wanted to ask the author if it's possible to drain mana from the Faceless One using the method described above, and also ask for advice on how to kill the boss.

Yes, you can, if you talk to Tas'netil, a secondary hero, and then start the ritual with Vol'diel on the same day. We'll probably need to remove the possibility of exploiting this. And regarding the boss - the hero was supposed to kill him alone. For this, a bonus to spellcasting is given, and the boss has a lot of health and high defense. But different approaches are allowed, of course :).