If my opponent has 4 cards in hand and i have 2 keep them downs. I commit them and do damage with my attack and my opponent discards 4 cards can I commit Yoshi to do 4 damage? Or would it be 2 damage.

Yoshi responds to one instance of discarding cards - since this example is 2 cards, then 2 cards, you'd respond to one of those and they'd lose 2 vitality.

Thanks Tag. I was thinking that would happen. I'm this as a consistent damage of 1 per turn. The only way for him to do major damage with is commit is to do a lot of damage. But the other thing that comes to my mind is that if opponent has no cards in their hands even if I do massive damage I couldn't commit for a fictional discard damage.