I see what people are getting at how the cards will affect players, how about as a mob drop? These cards can be dropped from zombies, skeletons, etc. Every mob has a different "trading card". Maybe even enraged have a higher chance at dropping?
As I said though, that wouldn't at all be easy to do, making a well-playable card game is difficult. Yeah, that would be the best option, I think.
What if: Mobs have a chance of dropping a random card (based on difficulty level) with some cards being rarer than others. Think of it like dragon fragments in how they are obtained. They should also just be renamed paper with some lore on them. The purpose of trading cards is to trade and collect them all. This would make them a very economy heavy item for the collectors of EMC and the economists. Making them playable would be more work than it is worth. Not only would rules and such have to be made, but the cards would have to be balanced and that would make things even harder.
