Energy
Energy cards are non-foil cards that are a subset of rare cards. Similar to rare cards, energy cards are more difficult to obtain than common cards. The number of energy cards per set of cards varies by the series.
Ways to trade:
1 Energy for 1 Energy
1 Energy for 2-3 Commons
1 Energy for 2-3 Story
1 Energy for 1 Rare
1-2 Energy for 1 Foil
2-3 Energy for 1 Promo