Complex sentence: Dexter returns home to collect his tools to attack Jordan, only to be surprised by Astor and Cody-they want to have Harrison's first birthday party in Miami and stay with him the coming summer.
Split into simpler sentences: Dexter returns home to collect his tools to attack Jordan. He is surprised to see Astor and Cody who want to have their baby brother Harrison's first birthday party in Miami and stay with him the coming summer.