Mercury was probably resurrected off-screen at some point, given how Onslaught attached to people who were resurrected to manipulate them, and we saw...
That exact storyline. At one point Rachel was holding back their zombie bodies telekinetically while telepathically attacking the goddess Morrigan. ...
That is not Rachel. The only arc or episodes Rachel appeared in was during the "Beyond Good and Evil" 4 part. She appeared as a captured psychic in a...