You can spend one gem to expand your card box capacity by five slots. Having room for more cards is always useful, especially when you need to save cards for evolving later in the game.
Card skills
After a specific number of rounds, some cards might gain access to special skills. If possible, save them for use on enemies with full health or on Bosses.
Cards
You can summon a special card from the "Summon" menu by tapping the chest icon with dragon head on the bottom bar. Scroll down under the "Gold Summon card" until you get to the free summon. This can be done once per day. By adding as many followers as possible you can earn Interact points. Once you have 200 interact points, you can trade them for a free card. Change your leader card based on what you need from it. For example, choose as a leader a card that gives your troops some sort of bonus, such as attack power. Only enhance your best cards, but keep each element balanced. Evolve your cards as soon as you are allowed to. Focus on the cards that you will actually use in battle for awhile. Use the cards saved in your card box to enhance or evolve first. When you have to, sell your extra cards. Enhance monsters one card at a time for a better chance of success compared to using multiple cards. Although it is more time consuming, it is cheaper. When you get 5 gems, spend them on a Golden Summon from the card summon box. That will give you a premium card that can greatly enhance your troops.
Combos
Always plan for combos when attacking. You will have time to change more positions of gems on the board. Always move when you can create a combo attack. If you can, find a match by moving one gem and keeping the other gem available for moving around. You can eventually build a lot of combos using this tactic. At times you will not have a complete deck and one type of color on the board will result in no attack. Never create a match of that color alone; instead, use it to create combos to at least double the effect of your other attacks. If you can create a match of at least five gems during a fight, you will attack all the enemies.
Deck
Compose a deck with all elements (red, green, blue, yellow and purple). This will ensure that every match you make will result in an attack. If you are missing an element, try to select your companion from the missing color.
Getting proper help
Before a quest is started, select another player to help you. If you are not satisfied with your choices, tap the back button and start the quest again. The list will refresh, giving you new choices.
Hearts
Do not waste heart gems by using them for matches while your health is almost or at full status. Save them until they can be used to their full potential.
Card box capacity...