I was using Wampa yesterday on VASSAL, and as he was attacking my opponent's A-wing (a great target for Wampa), my opponent claimed that Wampa's ability has to cancel dice AFTER his Green Dice cancel my Red Dice. He then gave me a link to a lengthy thread in this forum, which of course I didn't have time to go thru at the time. I just went with his interpretation, which basically made Wampa's ability useless.
Later, I read the thread he linked me to, and it seemed to come to the conclusion that Wampa cancels at the BEGINNING of the compare results step, which supports my interpretation that I can see him roll his Green dice, THEN choose to cancel my dice to trigger Wampa's ability or not.
I am posting here to verify that I am correct, and to bump the thread so maybe my opponent will see this so he won't rip off other players who choose to use Wampa.