How Do Training Event Work?
Once the event begins, you basically go to a separate screen and do training there. In training you can encounter a boss and choose to fight it. It starts at level 1 and each time you defeat it increase its level by 1. Increase in level just means the boss will have more health.
In a boss battle, you can deploy 1 of your unit and 3 of your allies. You can only deploy your allies once; if you would like to deploy them again you will need to "request assistance".
If you fail against a boss you can fight them again but it requires TP (training points). Failing against a boss will also allow you to request assistance from your allies. If they send you an assist, you will then be able to deploy them again. Sending an assist cost 10 TP.
You allies can also send you Soul Spikes, which does two things. It will reward the sender of the soul spike BT and Soul Shards. The second is that the next boss you encounter will have a reduced health.
You have 30 minutes to fight the boss again. Fighting a boss again cost 50 TP. Their health will be reduced by the amount you dealt them the last time you encountered them.
If you fail and do not choose to fight them again, after 30 minutes they will have fled. If they flee, the next time you encounter them, their level will be reduced by 1-3 levels.
If you defeat the boss you are rewarded with experience and a special type of item that can be accumulated to unlock prizes. In Soul Hunter these were Soul Shards and different bosses give different amounts. The higher the level of the boss, the larger amount of soul shards that can be earned.
Once you have accumulated a certain amount you can go to the "Reward" tab and click collect prize. Your Soul Shard don't disappear and will continue to rise. You can also sometimes collect Soul Shards in treasure chests.
Aura Spike: When your allies lose to a monster and ask for assistance, you can send a spike. This gains you 1,600 BT and 500 spirit shards. These are un-tradable.
Life Ward: It allows you to deploy more than one unit when used. (4 units?) These are tradable.