Mobs attacked the ninja. Force people is very small, and take a blow on the forehead is not an option. Convene a meeting, you decide to build defenses. Building will take place between them, and you will have a chance to survive all the waves of your opponent. For the destruction of the enemy you'll get the gold required for the construction of new towers. Just your sensei decided to sacrifice himself and he will personally stand on the strip and contain the enemy.