What's the point? You didn't do much? Sure your source may be copy-right free, but call it a hunch, unless you just happen to be Shane Mahan, creator and designer Iron Man, then your just using someone else's art. Sure, they may not pull it, but I've never been a fan of using someone else's art in a chop and I know I'm not the only one.

You are right but maybe my point of view that you allowed me to use and external source, I can called it anything else; The supernatural, the extreme force, ...etc. It's a source helping me in the picture not using another one art, maybe if you are right then all the external sources will be another one art (Castle, sea, forest, chair) which then you must do it by your own. I think that Iron man is a popular character and because of that you said that i'm using another one art, maybe if I used another character that you donn't know, I think it will be different opinion.
Thanks for the comment.