Complex sentence: Meanwhile, Black Bolt and Medusa tried to trigger the destruct sequence in the tower's central core unit, however, they were attacked by the Thors and Black Bolt ended up heavily injured defending Medusa.
Split into simpler sentences: Meanwhile, Black Bolt and Medusa tried to trigger the destruct sequence in the tower's central core unit. However, they were attacked by the Thor Corps and Black Bolt ended up heavily injured defending Medusa.