Hero Summon Defense

This is a tower defense game. In the game, your sole objective is to defend the defense line and prevent the enemy from breaking through it. You can continuously summon various soldiers. Two lower-level soldiers can be combined to form a higher-level soldier. By continuously merging, you can obtain higher-level soldiers. When facing danger, you can also summon multiple heroes to participate in the battle. Although heroes cannot be upgraded, their combat power is extremely high. The only drawback is that the cost of summoning is high and there is a cooldown period. In summary, you need to perfectly combine various types of soldiers to be able to hold this ultimate defense line.