Mahone pilotted it to the finals of a fairly well-attended league cup. However I personally can't get it to perform consistently (getting his build to produce a Magnezone early enough almost never happens for me).I ran into this once. It strikes me as that deck you either defeat quickly or struggle with if you cannot send up a ready supply of single Prize attackers. Which means it could ultimately prove viable, it now outright competitive. Having faced it only once, I don't feel like hazarding a guess.
