Complex sentence: After agent Armstrong explains to Tyler the effects that his trip into space had on his body, he shoots the ship, thereby critically damaging it, before revealing himself to be a reptile-like alien in disguise and captures Tyler.
Split into simpler sentences: After agent Armstrong explains to Tyler the effects that his trip into space had on his body, he shoots the ship, thereby critically damaging it. Agent Armstrong reveals himself to be a reptile-like alien in disguise and captures Tyler.