Codex is a quest but its a long one. These quest that i mentioned are easy to implement in the game. Just need internet, and implement some changes in that thing that we use to get the chest to the avatar and to the game.
The attribution of the reward is almost like in the arena. The part of the chest of course its all that is needed and getting a way to give them in the campaign. Of course these is when the reward is crystals and other items.
When is the boosts are the reward the way is the same has in the game.
sorry by my bad english. I am Portuguese.