IDR UL Ex IX 0008 BETA (or Number Eight) was an idr created by the mages at Rissberg Castle sometime around 1245. It took up residence in Magpie Forest for many years, killing lone travelers to the point locals knew only to travel in well-armed groups through the forest and its very existence spawned many scary stories about an evil presence there.
It was later killed by an unnamed white-haired witcher in 1373, when it was about to attack Nimue, who unwittingly tried to walk through the area alone.