So I know I have not seen many happy reviews of Atomos, and though I have not used him, I understand why there are frustrations.
I don’t have a great overall solution, but in facing him at full power a few times now I did have a small suggestion based on what I’ve seen.
I am facing a raid def team with Atomos and by some miracle of heaven he survives long enough to fire his special attack. With him and Zimkitha left I am resigned to target lion lady for five turns to avoid the resurrection feature.
I happen to fire a heal with a rebuff and those resurrection wings disappear. A completely toothless Atomos somehow just got weaker. I suspect there will be other changes, but this small one stood out to me. All that effort to get resurrection, it just feels like it should resist debuffing.
No real basis for the thought other than it annoyed me he got debuffed and I was the opponent it helped. Toss his owners a bone here, maybe more like several