Ultimate X-Men, Volume 4: Hellfire and Brimstone

The world tour is over. It ended abruptly and tragically, with deaths and hard decisions. After returning home to Westchester, the X-Men attempt to continue on, bringing normalcy back to their lives as best they can, opening the school to students once more. However, just as everything settles back to the mundane, Jean Grey's life shifts towards the bizarre. Her mental barriers are starting to erode, as she begins to see things... like a giant bird composed of flames. Ultimate X-Men (2000) #21-25.