Michael Nagy

FIREFLYS1, E9

Ariel

Simon offers the crew a proposition: if they help him sneak River into a hospital so he can run tests on her, he'll tell them where to find medical supplies that will fetch an enormous price on the black market.
BUFFY THE VAMPIRE SLAYERS3, E16

Doppelgangland

While casting a magic spell to help Anya regain her powers, Willow and Anya inadvertently summon Willow's evil twin, a vampire, from an alternate universe.
ALIASS4, E6

Nocturne

Sydney becomes infected with a mind-altering and potentially deadly hallucinogen causing her to slowly lose touch with reality. Vaughn and Jack must scramble to find an antidote before Sydney's hallucinations paranoia and resultant violent behavior threaten her life and the lives of those around her.