The Test of Time is the 37th episode of The New Adventures of He-Man.
Without Berilium to run its generators, Levitan, the floating city on Primus, threatens to fall from the sky and crash onto the planet. Treylus, the dealer and friend of Master Sebrian, journeys to Primus on his spaceship, the Star Trader to bring the required Berilium, but is intercepted by the Evil Mutants. Treylus is taken from his ship, the Star Trader and left aboard an inoperative shuttle in space. Treylus manages to send out a distress signal, which is picked up by a patrol of the Galactic Guardians, who rescue him.
The Galactic Guardians take Treylus to Primus, where he is reunited with his old companion Master Sebrian. After Treylus has explained the situation, He-Man, Treyus, Master Sebrian, and a few other Galactic Guardians go to Denebria, where they suspect the Mutants have taken the Berilium. Master Sebrian is impressed of the determination of the friend of the same age and wants to accompany him on his campaign to retrieve the Berilium.
When they arrive near Denebria, the Mutants attack the heroes of Primus directly, letting them know that they were on the right track. While a fierce battle ensues around Denebria's orbit, Master Sebrian and Treylus manage to land on Denebria and find the Star Trader. Treylus and Master Sebrian manage to outsmart the Mutants and capture the Star Trader. Because the freighter has no weapons, their hope rests on the speed of the ship.
When they reach Denebria's orbit, they find that they are so outnumbered that not even He-Man and the Galactic Guardians, can keep the Mutants away from the Star Trader. Master Sebrian uses a Voice Decoder to make his voice sound like Flogg's, telling the Mutants to return to base via radio communicator. Flogg cannot retaliate, because earlier he had grown angry and destroyed the control panels of his ship, disabling him from communicating with his Mutants. As all the Mutant shuttles return to Denebria, the Galactic Guardians and the Star Trader fly safely back to Primus.
On Primus, the generators of the flying city of Levitan are repaired, thanks to the Berilium that Treylus had brought.