On each level of the Dungeons of Doom
past 5, there is a 1/8 chance that a Leprechaun Hall
will exist on the level. Leprechaun halls don't generate ambient messages
, so you have to stumble onto it or use telepathy
Leprechaun halls are filled with sleeping leprechauns and their gold. If you can kill them all quietly, you'll amass a fortune. If they start waking up, though, you'll probably wind up in the hole by a large amount, as the leprechauns deftly relieve you of your zorkmids.
NetHack sadists are known for seeking out Leprechaun Halls with a fully charged wand of death. Pretty sick, but highly effective. Otherwise, magic missile spells or a scroll of stinking cloud will get the job done.