Keep ranking up until you hit rank 10 and you will unlock the arena. When you do you will be able to battle against other players for rewards, or against your allies for fun. There are new seasons of the arena at timed intervals, so come back when the new season starts to see what the new rewards are. You can earn rewards such as runes, rare cards, coins and LOTs of them, as well as Dragon Fangs and Dragon Stones.
Another way to earn more Dragon Stones is to invite people to the game or to get people to redeem your friend codes. If you have multiple devices to play this game on, install multiple instances and redeem your own friend codes on your main device. Post your friend code on the comments section of articles about this game as well as on review pages for the game, or Facebook. Or add people on Facebook and invite them to play the game, and if they accept, you get rewards.
After you evolve a card its level will be back down to 1, so it will appear to have lost statistics at first. However, that means that if you power it up again, it will gain levels rapidly again, being back down to level 1. Power it up to bring its level back up to speed, and the stats will skyrocket, leaving you with a far more powerful card than before the evolution, especially when you use same-color material cards.
You’ll unlock the daily dungeons around rank 7 or so, and when you do, you’ll be able to earn HUGE rewards from them. During weekdays they will earn you runes of specific colors, and during Saturdays, you will be able to earn massive numbers of coins from them, so if you have a hard time earning enough coins to pull off a good evolution or a power up using a rare Dieclops, then this is the place to go to earn enough coins to make it happen.
Your leader card should be very rare and a very high level, so that other players will pick it. The higher the level and rarity, the higher the chance of it getting the “Favorite” tag from the game, which will skyrocket your chances of getting your card picked. Also, to get players to pick it more, it should be a red card, since players tend to favor those due to their extraordinarily high attack power compared to other cards.
Sometimes you need to get unconventional during tough battles, in order to pull a rabbit out of a hat and beat a tougher deck than you. One of my favorite tricks is to get cheap attack cards of colors other than red (but that are physical attack cards). Green cards are the best for this. Use green cards which trigger attacks (and which tend to have a low magic cost compared to attack cards of other colors) and give them to your red creatures, and they will do a huge amount of damage for a low cost.
If you don’t need a hero card immediately, then save it for later on in the battle. This is especially true for boss battles. Let it sit in your deck for awhile, using other cards instead so that you can keep racking up the hero cards. Then when the boss comes and you need a big boost or a huge attack, start daisy-chaining the hero cards together, and chaining them with other support cards, in order to get huge gaudy damage numbers against your opponents.