Formation Training grants you EXP that can be used to upgrade your formation level. You receive 5 free training attempts each day. Once you've used all your daily attempts, you can obtain additional ones by either spending Diamonds or using the drill baton item.

There are three slots available to assign formation trainers, with one hero allowed per slot.

The first slot is unlocked by default.

The second slot can be unlocked by using specific items.

The third slot requires a certain VIP level to unlock.
Please note: If your VIP expires, the hero assigned to the third slot will be removed automatically.

The higher the hero’s star level and quality, the more formation EXP you can gain from training.