User blog comment:Reilock/Using Lol Images for other games: Thoughts/@comment-4593717-20131008153441/@comment-3974211-20131008180513

Fair use does not cover using the piece to advertise an unrelated product, regardless of whether it's free or paid for (although that is a subscription-based game, so they are profiting). "Fair use" covers non-commercial parodies, education, information, reviews, blogs, etc.