The only power that can stand against that of a Mary Sue are those of another. A Mary Sue that is self-aware. Tragically once a Mary Sue attains this status they fade away like ghosts in a week. Their visages becoming less and less visible, more and more transparent, as time passes. The Mary Sue vanishes completely at weeks end, leaving behind that which they were wearing and carrying at the time. 

We beseech thee Mary Sues. Please answer the call of heroism. The real call of heroism! Become self-aware and defeat those that cannot be such for they are hopelessly enraptured by themselves. None have ever laid eyes upon a Mary Sue though many have suffered at their hands. Perchance it may be that those that do are taken in to their reality twisting magic. Being forced to see and think what the Mary Sue wishes for them to see and think.

Go forth brave self-aware Mary Sues! For honour and glory!