Unicorns are a race of sentient creatures that came to the world during the Conjunction of the Spheres. They look like horses with a single, often spiral horn in the middle of their foreheads. They use telepathy to communicate with each other and (sometimes) with other races. Unicorn horns are universal antidotes to poison and can be used to detect poisons as well. For unexplained reasons, unicorns dislike elves.
Unicorns can only be captured by virgins. They also change colour with age. They can move between parallel realities, and they may also move through time (fourth and fifth dimensions).