Fatal Labyrinth/YMMV


 * Demonic Spiders: Wizards. They'll either confuse you or put you to sleep and allow other enemies to home in on you for the kill. Worse, they've got no apparent limit of times they can do this to you, and will often do so right as you recover from the previous spell.
 * Yet Another Stupid Death: As expected for the genre. Try reading an unidentified Sleep Scroll on floor 31, or drinking a Digest Potion when there's no food in sight, or tackling a dragon, wizard or robot-type enemy on low health. Fortunately YAAD is averted here - alarm tiles and pit traps are merely annoying and Ghosts and Mimics are easily avoidable (See Throwing Your Sword Always Works).
 * Considering the rarity of ways to cure oneself of an ailment or that there's an equal amount of nasty effects available from consumable items like scrolls and potions, using unidentified ANYTHING will invariably lead to YASD.