I don't think it would require much work either, I said daringly only having development experience in Hammer. Just simply add in spawn points that may or may not spawn, and like rogue-lites, have a mob budget that just randomly fills up when you spawn in. So you spawn into Tam-Tara and see a Garula trying to navigate the tunnels as a patrol. You can avoid it, but also heard somewhere the garlal can drop rare crafting mats or glamour items. Hidden caches that you can find by collecting clues around the dungeon. Hypertuned mobs you only want to fight one of at a time before because they got new abilities like voice of the Ram. A whole bunch of pain and rewards that sets the pace, and not about clearing it fast as possible, because it'd have no particular reward for getting to the exit, and going too fast will only end the run quicker. Tangent tanget.
Getting out of hand again, but it has a point to this thread. Deep Dungeons was were 3.0 Scholar and Selene shined like the brightest sun. Because while damage is more valuable than ever to kill things fast enough before timer runs out you barely had time to put up even one dot before tank's hp disappeared under a Sasquatch's critting fists, and Cleric Stance wasn't the default stance you wanted to be in because it's reduced healing was incredibly detrimental. It's also the kind of dungeon Selene was made for. Embrace, Silence, Aoe Esuna and haste every 30s. It all helped immensly and for all her hard work she was taken behind the shed and her dress given to Eos. Which is just the top of the iceberg of the mountain of issues I have with it's pruning. It had the skillset made for a sprawling open-ended dungeon where you can't predict everything and need to quickly adapt to traps debuffs and respawning mobs to prioritize healing, mitigating and Ruin II blind, Fey wind, Virus, dare to use Shadowflare for slow in a huge risk since a mob might walk into it before it's over etc. Deep Dungeons got around 80 floors where this fit right in and endless potential everywhere else, but SE keeps sandblasting Scholar until it's a spotless blob with a book that really wants to do Savage.