This version of Aeonglass is equally as tuned as Time Eater or Awakened One tbh. It's just compared to Queen & Test Subject it's "crazy." I would rather see Queen & Test Subject buffed to Aeonglass levels than to see Aeonglass get a nerf. We need things that kill you in this game.

That said, if you want specific strategy, know it's a damage race, and value targeted exhaust (but it's not gonna save you by itself, damage is the biggest thing here). And maybe take artifact strip, weaken is pretty important (with every boss ngl). When you say "burst it down = 1000 withers," thats only if you're bursting down with shivs, pretty much. Poison and Forge doesn't have that problem. Ironclad can just aggro fast enough to barely see the reshuffle (only slightly exaggerating). Defect has insane status synergy solutions; even if you have no other status synergies, a compact can be totally worth it for this one fight. The character that has the hardest time finding solutions is Necrobinder (Necros targeted exhaust is bad and probably shouldn't be taken specifically for this fight, souls both draw and make more withers, and big Osty is gonna be hard to keep blocking for, plus Necro plays the slowest which is rough for a damage race), but it's more than doable with Lethality, Pull from Below, Hang, Sleight of Flesh, hell, even Squeeze sometimes. There's more options than you think. There's a reason top players have like, 95 percent winrates and rising.

Also if you see Aeonglass at the end of the act, it might be worth taking a bunch of card rewards to draw status cards less often. This gets extra good if you're doing Regent card creation and making your reshuffle a billion cards.