Sources for letters credit are The Marvel Comics Index (Olshevsky 1981), The Official Marvel Index to the X-Men (Olshevsky 1987), The Official Marvel Index to the X-Men (Ward 1994), and Official Index to the Marvel Universe (Vandal et al. 2009).
Jack Kirby (layouts); Werner Roth [as Jay Gavin] (pencils)
The X-Men [Professor X; Cyclops; Marvel Girl [Jean Grey]; Angel; Beast; Iceman]; Sentinels; Master Mold; Dr. Bolivar Trask (Death)
With the X-Men captured, Xavier heads back to investigate a fallen Sentinel to try and figure out what stopped it; The X-Men escape and battle the Sentinels but it is the timely intervention of Professor X and the self sacrifice of Dr. Trask that stops Master Mold and saves the day.