Played about half an hour, got the dungeon to rank E, and I will be back for more. The loop really works. Watching a party walk into something you set up two raids earlier is a great feeling and it kept me going for one more attempt.
Two things got in my way. The tutorial is good but it never mentions teleport, so the first time it showed up afterwards I had no clue what it did and basically wasted a raid working it out. And there is a lot of clicking. Setting up rooms is fine the first few times, then it starts to drag when you are redoing it every raid. If there was a preset or a saved layout you could drop in it would help a lot.
UI needs polish in general, though I get that it is early. More traps too, I felt like I had seen most of the options fairly quickly.
Balance was fine for me at rank E, no complaints, just the usual thing where this kind of game lives or dies on not getting too easy or too brutal later on. Good luck with it, the core idea is strong.