Avengers vs. X-Men #11

Argumento

The X-Men defect to the Avengers and prepare to take on Cyclops and Emma. Xavier calls Scott out and tells him he will stop him by force if he has to. The Avengers and X-Men battle Scott and try to talk him out of using the Phoenix force. They hold their own until Scott turns on Emma and takes all of the power of the Phoenix for himself. Scott kills Professor X and turns into the Dark Phoenix.