A good deck is balanced. Aim for a mix of offensive and defensive capabilities. Ensure you have answers for common threats: air troops, ground tanks, and swarms. Your average Elixir cost should be manageable, typically between 3.0 and 4.5. Include a 'win condition' card (e.g., Hog Rider, Golem, X-Bow) that is your primary way of dealing tower damage. Don't forget a 'big spell' (e.g., Fireball, Poison) and a 'small spell' (e.g., Zap, Log) for utility and cycle.
