If the opponent has already drawn 2 prizes in the game, and then I use Dialga & Palkia LEGEND's "Time Control" attack to add two more prizes, how much damage would my Mismagius [GL]'s "Grudge" attack do on the following turn?

Even though the Time Control attack added two prizes to your opponent's pile, they have still taken two prizes during the game. So Grudge would do 20 damage plus 10 more for each of the prize cards they have already taken.

Relevant cards