Coins are currently used for the following purposes:

• Spam Prevention: You can only register an account after playing and winning a single game
• Buy Cards: Spend coins to collect extra copies of cards for your personal deck — browse the card shop
• Castle Skins: Customize the look of your castle with unique skins — browse castle skins
• Decorations: Add decorations like weapons, dragons and gems to your castle
• Wall Skins: Change the appearance of your castle walls
• More Features Coming: Additional uses are being developed!