Cards Upgrading & Evolving

Card Upgrading and Evolving by Fusion
  1. 1.
    Upgrading: Crystals, one of the in-game currency, can level up your cards to increase their power. Card rarity determines the number of levels: common (3 levels), rare (4 levels), epic (5 levels) and legendary (6 levels). Upgrading costs more as the level of a card increases.
  1. 2.
    Fusing: When you have two fully upgraded identical cards, you can fuse them to create a silver card (double-fused card). This one can be further upgraded with crystals. You can then repeat the process, using two fully upgraded silver cards to create a gold card (quad-fused card).
In both ways, card evolution results in increased attack power, greater endurance, enhanced spell potency (single-target spells can turn to multi-target spells), while the speed stat remains unchanged.