Before the county of Corvis, there was the Wizard Corvus. Thirteen hundred years ago, a mad powerful wizard had an estate in the area that became the county of Corvis. Over his 800 year span, he created thousands of magikal items of various types and power level, some of which survive to this day.
A slight rustle of the wind... and it stands before you. A Unicorn, whiter and more beautiful than you ever imagined it. It has deep wonderful eyes, and you can't help but admire this creature. It came to have a look at you, and now it freely goes. You have not the heart to stop it, and it silently vanishes between the trees.
Note: unless specially needed, this encounter should never happen again.