Well, as of right now, the dungeon is set to be the "hard" 3-floor version. Regardless of whether you skipped the generations or not. What I've been doing with moderate success is abusing summon pet/smash/return whenever hellhounds spawn and then clearing the rest of the monsters with magnum/counter. But one unlucky slip... and you and all the progress you've made are toast.
I've only made it up to the fourth room so far after six runs, so take that for what it's worth.
