Riurry, the greater black unicorn is a unique NPC found in a corrupted glade by himself. The PC must take the quest to kill him for the location to appear (though he won't be generated hostile). When chatted to, Riurry will offer a quest to slay his lawful counterpart, Yrruir. He will reward PCs that complete his quest with a stack of potions of gain attributes (said to be 3d3 of them), an amulet of chaos and some corruption (about 1-2 effects).