I am making a roguelike dungeon-crawler set in a cavern and I need some kind of hook to change up the gameplay a bit.
It feels like almost every hook has been done!

Right off the bat, if you feel like every hook has been done, think outside the box, a lot of mechanics hasn't been exploited, ask yourself offsetting questions, like what can you add to the detriment of the player, what part of the dungeon crawling formula can you change, remove, or change so much it's not recognizable anymore.