Necromancing the Stone

When Grams is summoned to call on the Halliwell matriarchs for baby Wyatt's wiccaning, she and the charmed ones fall prey to the Necromancer demon, played by Chris Sarandon. Also called "Armand" by Grams, he has returned from the spirit realm seeking to absorb the Halliwell magical spirits. The sisters also discover secrets about Grams' past love-life with Armand. Meanwhile Paige casts a truth spell on Nate to tell him she's a witch and finds out about his secret wife and two children. It is revealed that Grams was in a relationship with the Necromancer and loved him, but she ultimately banished him to the spirit world. The Necromancer wants to absorb all of the Halliwell matriarchs' power so he and Grams can come back to life, in love and immortal. The girls cast the truth spell on Grams, and it breaks the Necromancer's hold over her, allowing her to vanquish him with the ghost-vanquishing spell. The spell works because Gram's is a ghost, and only a ghost can make it work. With the Necromancer gone, she finally accepts Wyatt, apologizes to Piper and tells the girls Wyatt looks like their grandfather, who was in her words "a good man".