Linden is a hypnotic root that the Witch Hunter Eben used on Cassie Blake to make her lose her will in the episode Return. He was therefore able to control her and made her attempt to kill her father, John Blackwell. The spell used by Eben to activate the Linden was "Supinus Timeo". In the end, the Circle performed a spell with the help of Cassie to make her master of her will again.