After almost 1700 hours in Grim Dawn, I’ve finally managed to complete all the achievements, at least until Fangs comes out.

I must confess to cheesing it by completing the last three - Celestials - on Normal, after getting the floor wiped with my character a few times in Ultimate and not being sure what was going on, even with dodging sunders in what I thought was a reasonable fashion.
This is actually the third character I built with the intention of taking on Celestials. The first turned out to need some very specific MIs and, after making a half dozen mules just to hold all the ones that weren’t right in case I wanted to make some other Celestial killer build someday, I decided to try a no-MI build.

Character #2 was fun to play and based on orwund’s Conjurer. In the process of making over 30 runs through Morgoneth’s Folly to get the rings - and getting rings from 5 of the Magi - but none from Basti (or Sethris, but I don’t have any Phys Retal builds I’m planning on) - the last piece I needed for sk_choi’s Warborn Levithian Death Knight dropped. I never saw the amulet or the boots, for the Conjurer, either, and those aren’t target-farmable as far as I know.
It was an interesting journey, although I think I’ll be putting Grim Dawn down for a bit unless I get really tempted by the Badge of Perseverance. The hardcore achievements were more fun, now that I think about it.