Potion of paralysis
|A potion which eliminates your control over your own body.|
Quaffing a potion of paralysis paralyzes your character for 1d6 + 1 turns. Using it in the middle of a fight (because you've run out of options and are resorting to unidentified potion roulette) will turn you into a punching bag for monsters.
You suddenly lose the ability to move!
Potions of paralysis were removed in 0.15.