This is from the back-up story in Classic X-Men #7, by Chris Claremont and John Bolton.
The story begins at the Hellfire Club's annual gala.
"...to disarm one's foe by pretending friendship prior to an attack."
Shaw contacts Emma, who is at Shaw's beach house. He asks about Colonel Rossi, who they had rescued after his plane crashed. Emma tells him that she telepathically scanned his memories, and that his aircraft had been attacked by sentinels after Rossi's meeting with Steven Lang.
Suddenly a sentinel attacks the beach house.
Once they arrive, the Sentinel starts to spray them with nerve gas. Shaw starts punching down the remaining walls so the wind will blow the gas away, and to absorb the energy from the punches to make him stronger.
Harry Leland uses his powers to increase the sentinel's mass, causing it to sink halfway into the ground and allowing Shaw to destroy it.