u/DoriTheGreat128

Major spoilers for Abomination Vaults

So in AV one of the major bosses is this guy, and I can't understand how he's supposed to function. Also surprisingly, nobody in history appears to have asked about him on reddit

1. He appears to be doing exclusively persistent damage. It's entirely possible that it's a mistake and the intention is for it to be 2d8 (something) + 8 piercing, but it's also possible this is as intended, I just don't know how to deal with it. Persistent damage doesn't stack, thank god, but it will still probably kill my party who for some reason gets insanely unlucky on flat checks, if he makes even a few attacks. Which he might not because he's a spellcaster. It's also persistent piercing damage and not bleed so Administer First Aid doesn't apply
2. He has the swarm trait while also being (non-mechanically I guess) a humanoid. Some of the swarm mechanics probably apply, like being immune to grappled, but some probably shouldn't like the requirement to occupy the same square as someone to deal them damage.
3. This is not unique to him but I've never had it come up, so this is as good of a place to ask as any. What does unconscious immunity do? What happens if someone brings him to 0 with a nonlethal attack? Does he just die as if the damage was lethal, or does he remain conscious at 0 hp?
4. I have checked and my party has no splash damage and only really gale blast as an aoe spell out of those they typically have prepared. Unless Floating flame counts as aoe damage. So I don't know if they will be able to deal with his Discorporation effect, even if they get 2 turns. Any advice on that?

I suppose none of that matters that much, because he's a spellcaster primarily, his only weapon has reach and most likely no one will be using nonlethal damage unless the final blow is a punch to the face from our casters, but I can't run a statblock I can't understand and I spent hours trying to look this all up and came to few conclusions.