Crystals are either purchased from the Shop using real-world currency, or earned via Challenges. You can use Crystals to purchase Arena Pass, Cosmetics, or recruit new Hunters

Visit the Shop in the lower-left corner of the main menu if you wish to purchase more Crystals, or you can simply tap on the purple Crystal button located in the upper right-hand corner.

Credits, shown as the gold coin in-game, can be earned by completing Challenges as a reward. You can use Credits to purchase Costumes, Stickers, Victory Poses, and Weapon Wraps in the Customize tab.