Play the long wait cards at the correct moment. In longer battles, play a few quick cards first then use the long wait cards to make sure that they are not killed before you get a chance to play them. As soon as you have 100 gold, spend it on a card. It may be better than what you have, and if not, it will gives you extra upgrade points. Some cards can boost the stats of other cards, but only if they are of a specific race or class. You can determine a card's class by looking at the upper left corner, and the race from the card's color. Make sure to play them at the same time or you will waste a special skill.
Promotion
Tap the "Promote" button under the commander's icon. Artifacts are required to do this, and they can be obtained by battling against other players. Besides artifacts, you will also gain upgrade points for your cards.
Upgrades
Although expensive, it is best to upgrade your commander card first. Only upgrade cards you will use and always be in your deck. Only invest in the best possible cards. Fuse cards to get super cards. Fusion is the best way to win duels. Combine two or more cards in order to get a super one. Save cards that can be fused and do not sell them accidentally. You can get new commanders by doing this.