Complex sentence: Regardless, an assassin launches an attack at the speech, but is quickly subdued Doe, having earlier escaped Arkham during Vikki's riot, is seen sitting alone at a bar watching the event live on television and claiming that he has big plans in the future.
Split into simpler sentences: Regardless, an assassin launches an attack at the speech, but is quickly subdued. John Doe, having earlier escaped Arkham during Vikki's riot, is seen sitting alone at a bar watching the event live on television and claiming that he has big plans in the future.