Charmed and Dangerous

The Source (of all evil) is getting obsessed and desperate to find a way to defeat the Charmed Ones so he breaks an ancient agreement between the highest level beings on both the sides of Good and Evil when he unleashes the Hollow , a magical vapor-like cloud that consumes all magic power, but which oddity of magic can be taken into a magical being (inhaled, semi-possessed) to augment their powers for a time , to use against the Charmed Ones. One problem with the Hallow is that it continues to consume all magical power that it can tap, so must not be let out of a special container crafted to keep the magical universes safe. By violating this law, the Source threatens all of magic (and all life), which causes the Seer to decide that supporting him was beyond the pale and she begins to cast about for a means to cancel his control of the Hallow and replace him with someone she sees a great future for herself, as his adjunct: She and Belthazor (Cole) in one possible future make a great future for both sides with Belthazor at her side, so she begins to plot by abducting Cole to manipulate events to make him the next Source against his will and bring about the demise of the current Source. The Seer convinces Cole that taking the Hollow into his body is the only way to save Phoebe, but she doesn't tell him that he will become the Source. When the Source attacks the girls Cole covers Phoebe with his body to save her from the energy ball which makes him absorb the Source's powers, and thus also the Source himself to the Seer's greatest pleasure but unbeknownst to the Charmed Ones, and Cole only finds out after the fact when it's too late but says nothing.