Complex sentence: The students are sent via boats onto the dangerous island base of the Wild Seven, and a number of them are killed when they were bombed, shot or their collar detonated during the journey onto the island, leaving only a cluster alive.
Split into simpler sentences: The students are sent via boats onto the dangerous island base of the Wild Seven. A number of them are killed when they were bombed, shot or their collar detonated during the journey onto the island, leaving only a cluster alive.