Complex sentence: Tetch starts to brainwash all the attending politicians and dignitaries into obeying Talia; however, he is killed by a system overload caused in the ensuing battle between Batman's allies and Talia's henchmen, halting the process.
Split into simpler sentences: Tetch starts to brainwash all the attending politicians and dignitaries into obeying Talia. However, he is killed by a system overload caused in the ensuing battle between Batman's allies and Talia's henchmen halting the process.