Can this guy discard a shadow card after it has been opened but not resolved. I always thought that it can't but i just want to make sure.

What do you mean by opened? The moment you reveal the shadow is the exact time where you resolve it. So if it give +2 attack to an enemy it occur when the shadow is revealed. Discarding that card after revealing won't prevent the effect since it was already trigger (the enemy will still have +2 attack even if there is no reminder)

1 minute ago, Rouxxor said:

What do you mean by opened? The moment you reveal the shadow is the exact time where you resolve it. So if it give +2 attack to an enemy it occur when the shadow is revealed. Discarding that card after revealing won't prevent the effect since it was already trigger (the enemy will still have +2 attack even if there is no reminder)

That's what i thought. Thanks for the quick answer!