Training is the most efficient way for players to level an officer. The longer the training time, the more experience an officer receives. Short trainings cost only gold. Long trainings cost rubies.
You can get more experience per training by upgrading your Training Grounds. Your officers’ levels cannot exceed your player level.
Six training slots exist in total. In the beginning, you have only one slot. Players can unlock an additional slot at VIP 2 and again at VIP 9. You can unlock the other 3 slots by purchasing them with rubies.
You can perform power trainings after entering the Foggy Straight. A power training takes a very short amount of time, costs little, and gives plenty of experience. You can perform one power training every day. Players with VIP can perform up to 10 power trainings a day.