Starting at Level 11, you will get a quest to Invoke the Gods. You can either get this quest by pressing U on your keyboard and accepting the “New Task” quest or you can get the quest from Sergeant Knox in Protector’s Enclave. After receiving the quest, you’ll be asked to go to Aralynn the Pious to learn about invocation. She’s located relatively close to Sergeant Knox:
After talking to Aralynn the Pious, she’ll tell you to try out invoking. You will now be able to Pray or Invoke – go ahead and try it out! Press and hold down the CTRL key and I key on your keyboard at the same time to Invoke. Alternatively, you can click the icon near the upper right of your screen to invoke (be sure to press Alt first so you can freely move your mouse).
You can invoke once per hour and you will receive various rewards for doing so, ranging from free Astral Diamonds and Experience Points to random potions that can temporarily enhance your abilities. You can only receive Celestial Coins and Ardent Coins once per day, however.
Be sure to invoke at least once per day – this ensures that your Ardent Coins will not expire. While your Celestial Coins *never* expire, your Ardent Coins will expire in one day and five hours from your last Invocation. You can have a maximum of 7 Ardent Coins at any given time (or 7 days worth of praying) so be sure to spend them if you’re at your maximum of 7 Ardent Coins so that you don’t miss out on getting one.