The destruction of the Sept of Baelor, along with it the elimination of Cersei’s enemies upped the ante for the Great War to come. It was proof that Cersei was indeed Tywin Lannister’s daughter. No one could have pulled off something so cruel except the Mad King himself. 

All in all, Peppermint was indeed a simple story that lacked complicated subplots. However, the film’s main strength was its badass central character who carried the entire film with uncompromising efficiency. Simple plot + badass execution, after all makes for a strong action flick that goes perfectly well with popcorn and soda. And I for one, loved it.