Gold Rarity CardsGold quality cards are the third level. They are stronger than Silver cards and tend to be Final Cards. There are only 10 Gold quality Combo cards, Bear , Energy , Science, Time, Wind, Villain, Food, Life, Space and Monster were available from limited time Portals. And the All Hallows' Eve card which had to be bought from the Halloween Pack. A Gold card gains +3/+3 when it grows in level.
Combos that result in a Gold take 24 hours to research.