Through a Dark Circle (S01E11)

Driven by his longing for Shelly, Draven experiments with magic to reopen the loft portal. He believes he has succeeded when the door begins to glow. However, instead of reuniting with Shelly, he inadvertently releases the malevolent spirit of Richard Lee Wilbanks, a serial killer who seeks revenge on those who witnessed his execution. Wilbanks quickly overpowers Draven, stripping him of his regenerative abilities during their intense confrontation. As several witnesses from the execution are kidnapped, Detective Albrecht and his new partner, Capshaw, take on the investigation. Draven confesses to Albrecht about his role in unleashing the evil force, and when Cordelia, a former Assistant D.A. from Wilbanks' trial, is also abducted, tensions rise between the two men.