Finally got around to a bit more actually playing BN, and just barely scraped through one of Arcana's bosses that I'd recently buffed:
Basically, in
another recent tweak, I bumped the HP values of the main bosses from a range of 680-990 to 1000-2000, and adjusted armor values a bit, generally just rounding everything up (or sometimes down, if it'd make armor values vary more) to a multiple of 5. General goal was making the bosses last at least long enough against a better-equipped character to show off some of their special abilities, and making their armor vary enough to actually be meaningful.
My character had more in the way of tricks than raw brute force, compared to a late-game survivor. Mid-level combat skills, armor that's good but not really heavy enough to stand up to the dracolich in a sustained melee, and a weapon that's excellent against basic enemies but happens to be a piercing weapon with rapid strike against a boss that has an okay level of stab protection. But what I did have was a martial art that worked well with the weapon (in exchange for debuffs that meant I couldn't really dodge-tank), a few utility spells to level the playing field, and some charges of acid spray from the wyrmskin armor to add a bit more damage.
If I'd made use of the two summoning glyphs I had with me earlier than I did, I could've probably had a much easier time of it, as then I'd be able to keep back and make full use of the shrike's misericorde's pistol mode, but one of them died fairly quickly so dunno how long they'd actually last. If I'd waited to bring the copy of History of Alchemy I found there back home, I could've returned with citrine incense for some emergency stamina regen if needed to run off more easily, make some space to reload, re-cast some Magic Signs, etc. That would've been even more useful had I taken time to learn and probably level up an offensive spell, too.
So I think this test does give me a feel that this more or less accomplishes what it was supposed to. The dracolich lasts a lot longer, so I expect a better-geared character would find it more of a fair fight, unless you cheesed it with a LAW, or by just using clairvoyance and dropping target_attack spells on it from the other side of the wall, that one I don't really have any viable way to develop a counter for. But at the same time while it'll definitely mutilate an unprepared character, a more mid-game character like the one I brought against it can make it work by throwing every trick the mod gives them at that point, which seems fitting since I do like the idea of Arcana's bosses being trickery but having multiple ways to work around their various strengths.
About the only thing I'd change is make sure that the dracolich's "charred vomit" spell it sometimes uses instead of its breath weapon can't apply the corrosion status effect directly onto the target, because it's flavored as just a mundane "tried to breathe flames but failed" type attack, and I was wearing armor that's immune to acid.