a nice strategy for beating the higher levels is to use a portal burn type of deck, I made one that worked quite nicely. Use the usual cards (gold mines, crystal mines, etc.), but the goal of the deck is to activate a card like parting gift or kamikaze asap, then spam the enemy with controlled waves of peasants. The peasants will fall quickly, damaging the enemy portal with each death. It works nicely once you get the cards you need activated.
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