I read more of the wiki out of curiosity, and I got a couple of questions/suggestions regarding the mod's Ultimate Being form, if I may.
1) I have not seen mention of this, but do Ultimate Beings regain the ability to use Hamon, as opposed to losing it when one becomes a vampire? ...The wiki says nothing about it, yet Kars was shown to not only have Hamon again, but to have it much stronger than he did, described as wielding it with 'the intensity of the Sun itself'. May I suggest giving it back to Ultimate Beings, perhaps even with maybe a boost to Hamon itself, and Hamon-based attacks, if the form didn't do so already?
2) Aside from granting defense, do the Stone Mask and Aja Stone Mask have other purposes after being worn once and granting their wielder their powers, or are their wielders in possession of their full powers mask or no mask, with the exception of what defense they provide?
3) According to the wiki, Ultimate Beings begin losing life and being unable to move in space. While I fully get what you were going for here, namely accuracy to what actually finishes off Kars in the JoJoverse, isn't it a bit restrictive to bar access to an entire biome for whoever decides to use some very cool items from your mod? (And yes, there might not be tons of stuff up there in vanilla, but if someone plays with JoJo Stands, they likely play with other mods... several of which tend to populate space a lot more, lol) ...I think I recall reading somewhere that there was a way to return to normal human form which would grant the ability for one to explore space, and probably return to vampire/ultimate being later, so that's one way around it, but it's a bit... strange to do so in terms of immersion ("Ah, I need to farm X item in space. I guess I gotta become human again today").
Basically, my suggestion here would be to perhaps lower accuracy to the original subject a little in favor of playability. Maybe the user isn't frozen in place, but slowed down, making it usable even though we would be less efficient/effective in space? (Also I don't know how fast one loses health in space because I didn't test it yet, but if it was faster than that, may I suggest 1 Health per second in addition to making the user slowed down as mentioned just now?) In other words, making the user slowed down and making them lose health little by little would act as a limiter and a reminder of how Kars died as opposed to making an entire biome unaccessible in that form because it made sense in the series. Just my 2 cents, but I feel like this is one of them cases where sticking to the official content may be undermining the fun aspect where the Ultimate Being form is concerned.
4) In case you don't like my #3 suggestion, and/or just for the sake of information, how does one become human again after becoming a vampire/ultimate being? I swear I saw it on the wiki before, but I can't remember where. EDIT: Finally found where I'd seen it, namely much earlier in this here very thread. You said one could turn back to normal upon removing the Stone mask and then dying. Did that apply solely to vampires, or also to Ultimate beings?
EDIT #2: 5) I noticed that the wiki entry on The Hand mentions how the Hand's special ability, Erase Hand is 'broken'. Is that still true at this point?
Thanks for reading.