For me, it has to be mandragora swarms. They have unusually high hp for a swarm, have a bunch of immunities because they are plants, and do unblockable attribute damage, including CON. I have occasionally had luck giving them sacrificial summoned monsters to chew on while I rain devastation on them, but in general whenever I encounter them I curse that I didn’t buy Arsinoe’s entire stock of “greater restoration” scrolls, as I rarely have enough magic on hand to repair the attribute damage without a rest. It’s not like you ever have advance warning they’re around, it’s “ghosts and wild hunt guys, ok, wth, 4 mandragora swarms?!” I don’t mind monsters that do energy drain or attribute damage as long as there are countermeasures, and I don’t mind swarms that don’t have a couple of hundred hp and fast healing, but this combination is outrageous (and not Owlcats’ fault, I understand).
Does the Death Ward spell prevent the attribute damage from those swarms?
Not according to the PFSRD (I don’t specifically remember trying it in Kingmaker, but I think one run through I had Valerie with a helm with permanent death ward and she suffered the loss)- it’s a blood drain effect rather than a negative energy effect.
Any enemy that does permanent attribute damage is really annoying to me, and there are quite many such encounters, but I haven’t listed them.
The only viable solution is buying a lot of Restoration spells to fix that after each combat, indeed, and I’m not sure it makes any sense or adds anything to the game, really.
The defaced sisters in particular were bad for that as they impacted multiple attributes and could get multiple targets. I don’t personally mind attribute damage or drain (the permanent kind) as long as there is a countermeasure (whether I thought to use it or not) and there is some reason to expect it.
As to what it adds to the game, it makes more sense if you are familliar with the evolution of DnD from 1st edition to 3.5 (the basis of the pathfinder ruleset). Things like poison tended to be “save or die” in 1st and 2nd edition, which was about as popular as you’d expect. Just converting it to hit point damage wasn’t really satisfying either (as a high level character could just ignore quite a lot of poison), so attribute damage was introduced as a way to represent things where hp damage wasn’t a really good substitute and to preserve the idea that certain enemies (typically either poisonous or certain types of undead) were dangerous in an unusual way.
But wouldn’t a 12- or 24-hour damage be more interesting and more “realistic”? By the time the player meets those encounters, buying Greater Restoration scrolls or countermeasures isn’t an issue (though you have to keep that in mind and not forget). With a temporary damage, it will be more tempting to “live with it” until it wears off, or to rest. That’s more alternatives to casting the same spell multiple times or having to go all the way back to a priest to buy the spells.
But now I think I know the enemy I hate most, that would be the responsible for this!
Well, it was fun to find the solution, and at least it doesn’t happen not too often.