Couldn't you technically chain these? While the chances are super low, take an ideal example:
Knock out an EX, take 2 prizes. One of them is Greedy Dice, flip heads, take another prize (3 left). That prize is also Greedy Dice, another heads, another prize. Another Greedy Dice, another heads, another prize. Another Dice, another heads, another prize. That's all 6 taken off one knockout. Or, some silly chain with Ninja Boy into Umbreon for 4 prizes, 2 of which are Dice, both heads, that's game. While it doesn't seem competitive due to its reliance on lots of luck, it seems stupid enough to maybe work once online.
Knock out an EX, take 2 prizes. One of them is Greedy Dice, flip heads, take another prize (3 left). That prize is also Greedy Dice, another heads, another prize. Another Greedy Dice, another heads, another prize. Another Dice, another heads, another prize. That's all 6 taken off one knockout. Or, some silly chain with Ninja Boy into Umbreon for 4 prizes, 2 of which are Dice, both heads, that's game. While it doesn't seem competitive due to its reliance on lots of luck, it seems stupid enough to maybe work once online.