You will get 2 attempts at the beginning of the Adventure Event. Every time you start a cycle, you use one attempt, and when you complete a cycle, your progress will be reset. Your attempts are replenished at a rate of 1 every 12 hours and stop once the set limit of 2 attempts is reached. You can also purchase an extra attempt for 50 Gems (with a maximum of 7 attempts per week or event).