The Source's Oracle

A demonic female Oracle working for the Source of All Evil saw "a witch's call on the spirit winds" that the Charmed Ones (inadvertently) sent out, and Paige Matthews, their lost sister that could reconstitute the Power of Three. She warned the Source about this so he could get to her before them. ("Charmed Again")

Later, she helped the Source in his plan to get Piper Halliwell to read the power relinquishing spell from the Book of Shadows while in a simulated reality. As the Source was handling Piper, Cole Turner almost vanquished him with the largest and possibly most powerful energy ball in Charmed history, but the Oracle jumped in the way and sacrificed herself, taking the vanquish instead. ("Brain Drain"