So my current ideas involve setting up multiple level instances and letting the player cast "portals" between them. The portal entrances linger though, so as the level loops around you'll have to dodge the portals you've left behind on top of the enemies and obstacles.
There will be a limit on how often you can plane jump and jumping too fast, by either casting too quickly or by running into another of your portals will cause a type of damage. I think it will be separate from player health. Or maybe just decrease the playable running area.
Running through one plane still causes time to pass in all of the others, hopefully I'll be able to set up enough platforming that looping through the same few areas doesn't feel redundant.