Complex sentence: Shego and Kim proceed to mix it up, but during the course of the fight, one of Shego's blasts goes astray and activates the sprinkler system, causing the security shutters to open, and allowing Shego and Drakken to escape.
Split into simpler sentences: Shego and Kim proceed to mix it up but, during the course of the fight, one of Shego's blasts goes astray and activates the sprinkler system. Causing the security shutters to open, and allowing Shego and Drakken to escape.