Evolution
As you progress, you will gain the ability to rank up your player cards and eventually evolve them. Ranking up costs a large amount of gold and some rare materials. Each card has a maximum amount of ranks it can reach, but that cap can be increased by evolving the card.
Players
The overall power of a player card can be guessed by examining the number at the top right corner of his card. The higher the number, the better the player will perform. Note: This does not count training and gear.
Train your players to increase their base stats, which in turn increases their power. When you first start, you will only have one training slot. More slots will become available as you level up.
Each player has six equipment slots. You will get gear randomly by playing in Legendary Matches. A green highlighted equipment slot on the player screen indicates that new gear was obtained for that slot.