The staircase leads to Deep 2, which is treated as a new adventure. All Warriors start the new deep at full Wounds and all items and abilities with any "once per adventure" clause are reset, including Throg's Chalice of Night. Food items that have a chance to spoil at the end of an adventure will NOT be subject to this. Let's see if we can get Melkor to show up too, now that it's a new adventure...
Anyway, do you want to enter Deep 2 now? [Y/N]