I agree with your ideas for Twisted Flesh and Tainted Vessel, but Petrified is already pretty strong vanilla. I'm not sure it needs a buff, and it might be a little too much alongside the other two.

Demon Lord is a tricky one. Vanilla, it's not competitive with either of the non corrupted options so it definitely needs something but finding a balance is hard. Maybe giving them a taunt? One issue I have with it is that I don't think the other corrupted authority perks actually apply to the demons since they aren't 'followers' per se. It'd be nice if at least those perks applied to the demons as well, if such a thing is possible.

It would be nice if Demon-Lord just removed the decay timer on the Abyssal Call demons and allowed you to have them as permanent followers, then they’d benefit from frenzy.

I’m not sure those guys are powerful enough for the 20 perk, but they look cool, it just sucks I can’t actually use them.

I think the biggest issue with the corrupted vitality perks specifically is that you're giving up so much for mediocre replacements. For example, to get Twisted Flesh, you have to give up Fast Healer, and in return you get a small chance that maybe you'll ignore each incoming damage instance. For Petrified you lost a full 100hp for some immunity to status effects that you could easily mitigate in other ways. Not to mention to get there, you'd need to give up nearly 40% of your hp.

I like where you were going with the improved armor originally assigned to Twisted Flesh, though I think it needed a little bit of a buff from where you had it. Really though, what you've suggested about Twisted Flesh would be a nice buff *instead* of the armor mechanic, and then maybe if you took that armor mechanic and put it onto petrified (seems like it would fit thematically as well), so that taking both would net you additional armor, additional damage mitigation, and a small chance at healing. That would make it a much better deal for giving up boosted healing, 100 extra hp, and the extra loss to corruption.