ToME: the Tales of Maj'Eyal

In alt-nur level 3, the down stair case is not flooded like the rest of the level. I can sit there and rest without worrying about my breathing. A stair scummers dream...

If intentional, some indication when you step onto the square would be helpful (air seems to bubble up from the level below).

Is that a bug? I figured it was because it led to a floor that had air. It also gives you a chance to rest before fighting the boss.