Fortunately for you it's only 40 floors. And I'm pretty sure a few of the enemies don't actually respawn. But yeah, you definitely have your work cut out for you. Last floor is like 3 Darknuts simultaneously.
Yes, you will need the item from the sky temple before you can access the last set of floors. Without it, you can only reach like floor 30 or so.Ugh I think I can make it to about floor 25. I like to fill my bottles with that soup from the Ice dungeon and I tend to use all of my arrows by around the 15th floor. That last floor sounds like hell. Ps does it help if I finish the temple in the sky I think I have the Item from that temple but I cant remember.
The Ultimate Doom with Brutal Doom.
GET OFF SCUM
HOPE YOU ENJOY YOUR NEW ASSHOLE