However, other warlocks or sorceresses can learn to control and use Sidhe magic. For example, Merlin was able to harness a Sidhe staff, stolen from Sophia, to his own magic. The Witches of Meredor, considered by Gaius the worst recipes writers, created a potion that could force the faerie out of a changeling, and thus control one of the most important characteristics of Sidhe magic. The known characteristics of Sidhe magic are: