World War Hulk: X-Men #3

"Sworn to Protect" brings together X-Factor and the X-Men in a high-stakes clash with the rampaging Hulk, who's determined to take Professor Xavier. With Juggernaut at full power and the team pushed to their limits, it's a heartfelt plea from Mercury, one of Xavier's students, that unexpectedly turns the tide. Written by Christos Gage and illustrated by Andrea DiVito, with colors by Laura Villari and letters by VC's Joe Caramagna, this 2007 Marvel issue features a dynamic cover by Ed McGuinness and Dexter Vines.