Posting somebody else's artwork on a forum is hardly theft, if you state that it was by them, not you. It isn't stealing their idea or anything like that, because all you're doing is putting it on a website under their name, when you originally found it on a website under their name. It doesn't make it any more accessible to the general public, and it's not being used to make money or anything like that, it is just being used as a reference to their work. It would be the equivalent of posting a link to the person's original artwork. Putting the artwork in the actual game would be a different matter. In this case, the artwork is being used rather than just linked. I think that posting pictures from somebody else in the card art section of this forum is OK so long as the artist's permission is gained if the artwork is to be added to the game itself, and you post a link to their original artwork post in your topic.
