I would like crossovers where protagonist uses powers from another universe but is not godlike, or gets OP too easily and too fast. Something like In a different world with Naruto system only way better, not xianxia'ish and definetely at least 1000 times better than God of Soul System. It doesn't have to be a system though... A lot of chaps and ongoing, or completed. The fics getting crossed should be well known like Naruto, One Piece, Dragon Ball, Bleach, Devil May Cry, Star Wars and uh Harry Potter(though idc really for such weak magics) Worm is okay I guess but I don't want that lame mc- worm, and no RWBY.
It’s Impossible that My Evil Overlord is So ... MC is implied to have transmigrated become OP and adopted the defeated demon lord and then returns to Earth. However, there sort of is magic in the world, just that it's more xianxia-like? Anyway, the MC's magic is different from the ambient one. It's enjoyable; the MC is OP but in a way that does not make the story boring.
You aren't supposed to find fanfictions on NU (even if nowadays there are way too much Cn "authors" shamelessly trying to make money while stealing popular characters of other writers or mangakas while trying to pass of jumbled fancfictions and blatant original characters rip-offs as original novels or contents that are translated and listed here in novel updates ). So you'd better go on places like fanfiction.net or other fanfic specialized websites for this kind of stuff...