[Cooptastic]

*Nica enters the library and approaches the Librarian and asks them if they have any literature regarding black unicorns, whether they be myths or factual accounts of people encountering them*

[Gmork]

It is said that Unicorns dwell deep within forests and shunned most creatures, only conferring with fey such as pixies, dryads, and sprites. They usually showed themselves only in defense of their forests. It is said that true unicorns are white.
Black Unicorns, it is rumored, are evil corruptions of these creatures. But there is no definitive information on them or if they are anything but myth.

[Rainman]

I don't know if this helps, but I found a reference to a Black Unicorn sighted in the Dark Woods near Sullivans Trading.

The source can be unreliable at times but a lead none the less

Albert Pendragon, Master Librarian