I set the app. to go to dungeon which one can do once an hour (if not using mushrooms) but couldn't make it. Set only the checkbox to enable dungeon, didn't work. Tried to also set level diff. to -99, also didn't work.
I don't know how it works elsewhere but on Hungarian servers there's a "Dungeons" ("Kazamaták") button, no way to select an opponent but need to kill the monster popped in the offered order, 1 to 10., in other words it follows the list given here: