Unicorn
A unicorn, represented by u, is a type of monster that appears in the dungeon starting at mid-game. They are very fast and tend to prance around, which often makes them difficult targets. They can also deal surprising amounts of damage.
There are three types of unicorns: white, grey, and black, which correspond to lawful, neutral, and chaotic alignments respectively. The unicorn of your alignment will be peaceful; all others will be hostile.
When killed, a unicorn leaves a unicorn horn with its corpse. Eating a unicorn corpse has a chance of giving poison resistance.
Sacrificing a unicorn at an altar is a special case; to receive alignment and luck benefits, you want to sacrifice a unicorn of a different alignment than you at your own altar - for instance, if you're lawful, you would want to sacrifice a grey or black unicorn at a lawful altar. Anything else has bad results. In particular, if you, as a lawful character, sacrifice a white unicorn on a chaotic altar, the result will be converting you to the Chaotic alignment. If you offer a grey unicorn on a neutral altar, you will be set upon by a slew of elementals. If, however, you offer a grey unicorn on a chaotic altar, you will automatically convert the altar.
Throwing gems to a peaceful unicorn can bring luck increases as well as assist in identification (if the unicorn "graciously" accepts your gift it is worthless glass; if he "gratefully" accepts your gift it is a valuable gem".)
