Charmed - Season 4 Episode 8 -

Paige brings a baby-robot and gives it to Piper and Leo to see if they can conciliate having a baby of their own and vanquishing demons. Meanwhile, the Halliwell sisters are chasing a demon that kills witches from the same coven with his Athame, a weapon used also by Belthazor. When they face the powerful demon, disguised as the District Attorney Sykes, Cole needs to leave his human nature and unleash his true demonic nature at all to vanquish his replica, paying a price for his action.