Charmed - Season 8 Episode 22 Forever Charmed Once lucky, Twice smart, Three times Charmed
Overview: Piper & Leo, with help from Coop's ring, must travel back in time to change the events that lead to the deaths of Piper's sisters. Meanwhile, Billie uses her power of Projection to do the same thing; many familiar faces gather to help Piper in her time of need.