>>125352911There is another magic system inferior to Miraculous magic which runs on faith (ex: guy can poison you with olive oil by relating it to Christ's suffering in Gesthemane). It's inferior because Ladybug's yo-yo can cut through barriers, the Miraculous suits mitigate damage, etc due to Kwami magic being very old. There is an exhibition on ancient France that is drawing in magicians good and bad, LB and CN have to team up with the good ones and fight the bad. Turns out one of the swords on display is actually the key to the gates of Ys which was a mythical French city which was flooded by the devil. They key unlocks the primordial Abyss, causes Ys to materialize above Paris, and releases like it was an SMT game or something. Final villain is the guy who unlocked Ys, functionally serving as the human avatar of the Demiurge.
It's mostly an excuse to incorporate European myth and cool Paris stuff like the catacombs into ML while upping LB and CN's heroics to ridiculous, apocalypse-averting levels.
I decided to build my own world for the story concept and write it as a light novel concept. 6 arcs and two side stories each 200-400 pages long. The Paris arc pre Ys revival and the fallout of it are now the seventh and eight arcs because I need to build up a whole new world and characters before the finale. The new MC is a lot more like a cross between Gintoki from Gintama and The Doctor from Doctor Who than Ladybug. He teams up with a cop who eventually gains a symbiote suit type power and an orphan witch girl in the first arc and they make a sort of found family unit. Villains are now reincarnated humans who learned Angel-tier magic that want to almost completely sink the human world into the Abyss before shooting straight through it to reach the Gnostic concept of the Pleroma (this is because if you try to cross it normally your existence will be dispersed by the demon Choronzon).
If you are familiar with A Certain Magical Index I also borrow heavily from it.