Me and me friends get them every time in the pvp free matches and the real pvp matches. What we had was all Life Students and Death or Thunder as pur back up school making us partially invinceable to any attack they throw at us. And that's not even counting to our treasure cards which were a lot of attack shields, Krakens, Healing light, meteor storms, and scarecrows. You don't have to follow my idea of this but if you don't belive me we were undefeated so far in the pvp matches.