almost never...I got the molten armor ( the most powerful one ) and I get killed most of the times...even with 6 feral claws and the murmasa ...mursama...marsuma..anyway it a fast broadsaw unique sword and with the sun flail thingy...the most powerful flail...and still I am getting killed...
If you got into underworld and survived for more then 10 mins, then you are really ready to go into dungeon...bring lots of potion...there is enemies everywhere...flying skeleton heads...casters that spawn constanly and skeletons fighters...with kind of red armor...
bring lots of potions