Page "Phoenix Force (comics)" Paragraph 26

The Age of X reality was created when Legion's mind reacted to Doctor Nemesis ' attempt to restore its sanity.

A new persona, with new powers, was born creating the new reality in order to protect Legion's many personalities.

This new manifestation of Legion's power took the appearance of Moira MacTaggert, in order to confuse Xavier and protect Legion.

In this reality Jean Grey's Phoenix Force ability manifested causing a tremendous amount of destruction and death in Albany.

Though she was presumed deceased when the Air Force bombed the area, a new phoenix shape emerged from the rubble.

Under the name of Revenant, it is not known whether she is Jean Grey ( presumably dead after the Albany incident ) or a totally new incarnation.

She joins Magneto and became part of the Force Warriors.

She also states she got lost on her way home and she does not look like herself.