A-Z of Marvel characters

Whilst I have an (unhealthy) advanced familiarity with these characters and the themes and ideas they present I'm struggling to find a overriding theme for my poster with this idea, outside of a generic superheroes fighting poster. As I want to make something a little different and more comedic I'm not sure this is the best idea to move forward with. I'll save my comic nerd-dom for a more fitting brief I think.