in the Marvel Encyclopedia, Doom has the edge in intelligence, speed, durability, energy projection, fighting skills and is even in strength so in a straight up fight I guess he'd give Rider real problems...however Rider's Penance Stare would cause Doom to feel all the emotional agony he's caused others (obviously that's off the charts)...Doom has knowledge of the mystic arts and might be aware of the fact Rider's alter-ego Johnny Blaze are in conflict with one another and could capitalize on that...I think Doom wins if he has prep but would have to flee if caught off guard and confronted with all the pain he's caused the world...does anyone know if they've ever met?