"The Supreme Sacrifice"
Reprints X-Men #16
The X-Men are prisoners of the evil Master Mold, unable to escape his fortress as Master Mold finally convinces Trask to create more Sentinels. Meanwhile, Professor Xavier attempts to learn why one of the Sentinels collapsed and eventually figures out their weakness. Although the X-Men make their escape and take the fight to the Sentinels, they loose the upper hand and it is Charles Xavier to the rescue. Trask turns on Master Mold, destroying the replication device and killing Master Mold and himself in the process as the X-Men escape the Sentinel stronghold and certain doom.