S1·E39 The Captive Comet

Haggar locates and takes control of the Omega Comet, a legendary black-hole-like structure which crushes and destroys anything in its path, and sends it for Arus. Though Voltron redirected it once after a decade of trying, the Voltron Force are forced to race against time to move it themselves after they get Romelle's warning. Seeing Allura's cousin's loyalty to them, Lotor mentions that a certain control-function will help them in front of Romelle, and she relays the information to them. But it was a trap Lotor had her lure them into, and they crash-land and are stranded upon the comet without power. The Galaxy Alliance can send no reinforcements thanks to Zarkon's fighting. But Bandor goes against orders to stop guarding the power-supply he was posted in front of to repay his comrades. The Voltron Force cannot escape, and conclude that Bandor must use his arsenal to strike the comet away from Arus - though they know it means self-sacrifice.