So imagine that, some time in the future, players are given a level editor of some sort. We are given the ability to create either a level pallet (ie, clockwork tunnels, devilish drudgery, concrete jungle), or create rooms (ie the connections and parts of the levels encountered).
However, no matter how many things we have access to, we will eventually run into a wall of "this has been done already". There's only so much you can do with switches, pressure plates, doors, ghost blocks, etc.
So what sort of interesting mechanic would you add into a PvE environment to spruce up puzzles? Can be fast paced, slow paced, anything really.
Add spawning boss(es) in scenario rooms and have them triggered by a party button. Action guaranteed as well as renewed fun.