Complex sentence: At this point, Altair is annihilated by a newly powered up Sirius, who then steals the Omni Cube and escapes to his secret lair to destroy Planet Bomber.
Split into simpler sentences: At this point, Altair is annihilated by a newly powered up Sirius. He then he takes Omni Cube and escapes to his secret lair to destroy Planet Bomber.