The Throne Marked by God

This is a world where there are 4 subclasses - magicians, knights (order and guard knights to choose from), assassins, summoners, warriors and priests.
Each subclass has its own temple or school-temple of knights, temple of ososins, temple of summoners, temple of magicians, temple of warriors and temple of priests. Every 10 years, a competition is held where they are looking for 3 teams of 6 people to send them to war against demons who want to seize human lands.
Think about yourself and go to the competition

What are the rules?
The world of the series is in a state of constant war. Human civilization has long struggled with demons, and ultimately the balance of power has evolved as follows:
The Temple of the Six Saints is the organization that coordinates the defending knights. It is through them that the people attempt to resist the invasion.
A hierarchy of power. There are different levels of might: from ordinary knights to gods and demons. Power is not given forever—it must be constantly increased through training, rituals, and the use of special artifacts.
A clash of forces. The key conflict is the struggle of humans against the demon emperor Feng Xiu and his army.
Spiritual energy (mana) is the basis of strength. Characters' strength is measured in units of spiritual energy, which is increased through training and trials. It is this energy that allows them to use abilities and activate powerful items.
A system of knight ranks and classes. Knights have levels and specializations, with advancement linked to increased spiritual strength and passing trials.