Complex sentence: Before Wheeljack can get to him though, Seaspray is killed when a bomb planted on his ship by Dreadwing detonates and his death motivates Wheeljack to pursue and apprehend Dreadwing.
Split into simpler sentences: Before Wheeljack can get to him, Seaspray is killed when a bomb planted on his ship by Dreadwing detonates. Seaspray's death motivates Wheeljack to pursue and apprehend Dreadwing.