Complex sentence: In "Homefront", he returns after the team survived an attack in Mount Justice by Red Torpedo and Red Inferno, only to seemingly re-activate the androids and attempt to murder the heroes by draining the room out of oxygen.
Split into simpler sentences: In "Homefront", he returns after the team survived an attack in Mount Justice by Red Torpedo and Red Inferno. When Red Tornado approaches the deactivated androids, he seemingly re-activate the androids and attempt to murder the heroes by draining the room out of oxygen.