Complex sentence: Davian triggers the micro-explosive in Ethan's head, but Ethan kills him and the jury-rigs an impromptu defibrillator to deactivate the explosive.
Split into simpler sentences: Davian triggers the micro-explosive in Ethan's head, but Ethan manages to kill him. Ethan jury-rigs an impromptu defibrillator to deactivate the explosive.