A unicorn is a type of monster that appears somewhat early in the dungeon. Unicorns are extremely fast (even to a player with intrinsic speed), and move in order to stay a knight's move or more away, so as to be out of range of both melee and ranged attacks. If the unicorn is pinned down in a corner, it may teleport away before the player can approach.
There are three types of unicorns: white, gray, and black, which correspond to lawful, neutral, and chaotic alignments respectively; directly killing a unicorn of your own alignment always carries a −5 Luck penalty. Eating a unicorn corpse is safe regardless of alignment, and has a 27% chance of giving poison resistance.
Normally generated unicorns matching your alignment will be peaceful; all others will be hostile. Unicorns in bones files or created by polymorph traps may be exceptions to this rule.
When killed, a unicorn is guaranteed to leave a unicorn horn with its corpse, unless it has been revived or is a polymorphed monster from a polymorph trap, in which case it has only a 50% chance of leaving one.
Unicorns do surprising amounts of damage, getting in multiple kicks and butts per turn. However, because they will not intentionally move into melee range, it is usually not difficult to avoid combat with them. This does not apply to pet unicorns, who will attack monsters normally as any other pet would. Attempting to move into melee range of a non-peaceful unicorn will cause it to usually attack you before leaping or teleporting away to an applicable square.
In the beginning of the game, when you typically are weak and need the horn, the most sound strategy for fighting unicorn is to let a pet take it out; this naturally also avoids any Luck penalties. Attacking with projectiles and rays which bounce from walls is also a good way to hit a unicorn, as is trapping it using either a pit or a beartrap (though it will only work once per trap) - a boomerang can be handy in this situation as well. If none of these options are available, try having it follow you down a long hall while you fire at it from a safe distance.
If you are skilled or better in polearms or lance, you will be able to use one to attack the unicorn after it moves a knight's move away from you with no fear of counterattacks. Players with very fast speed will have occasional chances to attack with ranged weapons or else close in to attempt direct combat, and a well-armored and prepared one can defeat them fairly easily.
A good way of closing in on a unicorn is to use invisibility or displacement: unicorns cannot see invisible, making for a much easier time lining them up to throw weapons or gems at them. However, invisibility can backfire for a weak character - a hostile unicorn that can't see you will not know to stay a knight's move away, resulting in a potential skewering if it closes in.
Applying a unicorn horn has a chance of curing blindness, hallucination, confusion, and stunning status effects, making a unicorn horn an essential item for all adventurers - see its article for more details.
Unicorns can use their own horn to cure themselves of these effects, producing the message "The tip of the <color> unicorn's horn glows!" A player polymorphed into a unicorn can use the #monster extended command to do the same, acting as a noncursed unicorn horn would.
Sacrificing a unicorn at an altar is a special case and is covered in the page on sacrifices. Simply put, to receive alignment and Luck benefits, you should sacrifice on your own altar a unicorn of a different alignment. If the corpse, the altar, and you are three different alignments, it is just a regular sacrifice. Sacrificing coaligned unicorns, as well as sacrificing any unicorn on an altar of its own alignment, will cause bad things to happen.
Unicorns and gems
Throwing any gem to any hostile unicorn will make it peaceful. A tamed unicorn will catch and immediately drop gems thrown at it, without any effect on Luck or identification. Unicorns also pick up any gems and stones they come across, worthless or not.
If the gem is worthless glass, a rock, or a gray stone, it will not affect your Luck, and the unicorn will either "graciously" accept it or be "not interested in your junk". If it is valuable, a co-aligned unicorn "gratefully" keeps the gem and improves your Luck, depending on the identification status of the gem: +5 points if the gem is formally identified, +2 points if type-named, and +1 point if completely unknown.
This makes coaligned unicorns great for improving Luck and sorting out worthless glass. The game does not check what the gem is named, or what its type is called, as long as one of them is defined - therefore, you should type-name all gems before throwing them at coaligned unicorns.
A cross-aligned unicorn will "hesitatingly" accept a valuable gem, and your Luck may increase or decrease by one point if the gem is not formally identified, and by up to three points if it is. It is not generally a good idea to throw gems at cross-aligned unicorns unless you're pretty sure they're glass.
It is easiest to fling gems at a unicorn in a non-teleport zone, e.g. Sokoban, in order to prevent them teleporting away after each catch.
If you are sure you will not need the unicorn again, you may want to encourage a pet to kill it so you can recover your gems without any Luck penalty.
- The <color> unicorn's recently regrown horn crumbles to dust.
- A revived unicorn died, but did not drop a unicorn horn.
- The tip of the <color> unicorn's horn glows!
- A unicorn cured a status problem using its horn.
- The <color> unicorn catches and drops the <gem>.
- You threw a gem at a tame unicorn.
- The <color> unicorn is not interested in your junk.
- You threw a formally identified or type-named piece of worthless glass, a rock, or a gray stone at a unicorn.
- The <color> unicorn hesitatingly accepts your gift.
- You threw a valuable gem at a cross-aligned unicorn, and your Luck may have gone up or down.
- The <color> unicorn graciously accepts your gift.
- You threw an unidentified piece of worthless glass or a gray stone at a unicorn.
- The <color> unicorn gratefully accepts your gift.
- You threw a valuable gem at a coaligned unicorn, and your Luck increased by 1, 2, or 5.
In lore, the unicorn is an almost unattainable target, nearly impossible to catch. Its horn is commonly depicted as being sought after for its various magical properties.
Men have always sought the elusive unicorn, for the single twisted horn which projected from its forehead was thought to be a powerful talisman. It was said that the unicorn had simply to dip the tip of its horn in a muddy pool for the water to become pure. Men also believed that to drink from this horn was a protection against all sickness, and that if the horn was ground to a powder it would act as an antidote to all poisons. Less than 200 years ago in France, the horn of a unicorn was used in a ceremony to test the royal food for poison.
Although only the size of a small horse, the unicorn is a very fierce beast, capable of killing an elephant with a single thrust from its horn. Its fleetness of foot also makes this solitary creature difficult to capture. However, it can be tamed and captured by a maiden. Made gentle by the sight of a virgin, the unicorn can be lured to lay its head in her lap, and in this docile mood, the maiden may secure it with a golden rope.
Martin took a small sip of beer. "Almost ready," he said.
"You hold your beer awfully well."
Tlingel laughed. "A unicorn's horn is a detoxicant. Its possession is a universal remedy. I wait until I reach the warm glow stage, then I use my horn to burn off any excess and keep me right there."