How to increase max levels of my heroes?

League requirements

The maximum level is a mechanic when you cannot level up your hero above a certain level.

As you progress in the game, you increase your League, and need to strengthen your Heroes in order to be on the same level with your opponents.

How it works

As you can see on the screenshot below, there are enough Hero points, but the Hero cannot be leveled up:

If you open the Hero info tab, you will see the conditions for leveling them:

As soon as you reach the required League, you can continue to level your Hero up further.

Breakthrough mechanic

This mechanic is found at certain levels of Heroes: in order to keep leveling the Hero up, you need to make a Hero Breakthrough for them to receive stat bonuses.

Gold and Power Essence are required to make a Breakthrough.

The level, on which a Breakthrough is required, can be seen in Hero's info tab: