Unnatural Resources/Plot

Plot
The sisters are in Magic School discussing how to kill The Source, who has recently come back to kill the sisters as a golem. They explain to Coop how they defeated him the last time; however, clearly it wasn't enough to kill him once and for all. Piper suggests using all the power of the white magic practitioners in the realm to destroy him. They suddenly hear violent thumps on the walls around them and find out that The Source is trying to break through the school's protective shield that wards off evil by firing multiple fireballs, however, it fails.

Piper insists that Paige orb to every magical creature they have come across over the years, starting with Coop, and collect a bit of magic from each of them, thus making the strongest potion ever. She gives her the phosphorus cauldron that is able to collect every bit of magic.

Meanwhile, in the Underworld, Neena is preparing some kind of potion for the source, while Hogan is worried that he won't be able to get into The Source's inner circle. If The Charmed Ones don't defeat him, however, Neena has something bigger in mind and tells Hogan that The Source shouldn't trust them. The Source is still trying to get through the protection around Magic School while Piper tells Phoebe to go through every page of the book to find a spell that can finally vanquish him and get him out of their lives once and for all.

Leo thinks Piper might be able to at least wound him with her new power, however, with him being stone, it's highly unlikely. She then gets an idea and with Coop's help they beam back to the manor and she reveals Excalibur, which should be strong enough to wound The Source.

Paige is still collecting little bits of magic from every magical creature, including: Mermaids, Fairies, Nymphs, Leprechauns and a unicorn. She had also orbed Billie back to San Francisco for her to help out. At Magic school, Phoebe is still studying the book trying to make up the most powerful Power of Three spell ever. Coop and Piper beam back with the sword, and Piper insists Leo takes the children somewhere safe and out of harm's way. By this time, Phoebe has nailed the new Source vanquishing spell. Neena and Hogan have nearly finished their own potion for The Source, as well, although Hogan is questionable about the whole plan, which annoys Neena immensely.

The Source's attacks are now breaking through the protective shield causing rooms to catch on fire. The Charmed Ones hurry out their husbands and Tyler, who wants to stay and fight, until Leo convinces him to go. Just when they leave, The Source breaks into the school and Paige puts up her Orb Shield to protect her from any flying debris. Piper uses her new power to melt a rope, temporarily distracting him from Phoebe. She levitates and throws the potion at him, which gives Piper the opening to stab him with Excalibur. Paige throws another potion and they all hold hands. They chant the new spell and Paige creates her orb shield again, protecting them from the now vanquished Source.

At that very moment in time, Neena casts a spell that gives her, as well as her demonic gang, The Source's powers, making them extremely powerful and possibly unvanquishable. Still annoyed with Hogan, she puts an end to him once and for all, killing him with vines, which in the end, choke him to death. However, the true identity of Neena is still unknown.

Everyone goes to Piper's New Restaurant and talk about being free from the Source finally. Grams appears and greets her grandchildren. They talk about when the little ones are going to come into their powers. Piper seems to think that Melinda is going to come into her powers sometime soon. Right on queue, Melinda attempts to reach out for her teddy bear, and, upon being unable to reach it, orbs it to herself, without anyone noticing.