I’ve made a modified version of this WIP homebrew and it does fit your desire as when I saw it I had the same idea as well. I have been wanting to make a more advanced Power System for Open Legend since the beginning as seen with my very old Advanced Open Legend homebrew. I took Yv’lin’s Spellcasting rules and made it more generic and less specific, instead of yv’lin’s spellcasting, it is simply called the Power System. Built to accomodate for any kind of Power System, from Spells, to Nen, to Stands, to Quirks…! Anything.
Been playing with it for some time now and had lots of playtesting but I never bothered to share it because it was only ever meant for our personal use and I technically stole the rules from @VanGo here. I didn’t think it would be a very nice thing for me to just show off a homebrew of a homebrew. I’d consider it plagiarism.
Oh and also I don’t think the rules are very balanced, they may be just as bad as Advanced Open Legends! (lol) so that’s another reason. Lots of play test doesn’t equate to good balance, especially when you suck at math and psychology as much as I do!
If it turns out it’s okay for me to share it, then maybe I’ll post it somewhere after a little bit of polishing in the writing and removing some of the extra homebrew stuff written there that isn’t related to the Power System…