Shakti

Shortly after the birth of Chris, Piper Halliwell and Leo Wyatt go to a Hindu wedding after being pressured into it by Phoebe and Paige. At the wedding, shortly after their arrival, two bright lights appear and fly into them. Piper suddenly grows four extra arms and is now the Hindu goddess Shakti; the god of creation. Leo turns into the God Shiva, the god of destruction. Later, after Piper had killed all of Barbas' minions, Paige removes the gods from them with a spell. ("A Call to Arms")