Use a bow to defend against zombies. Hordes of zombies will try to destroy your tower. Some of them are faster, but have less damage and lives. Some, on the contrary, are slower, but have a lot of damage and armor. By destroying zombies, you will receive mana for two abilities. The first one will allow you to shoot arrows continuously. The second one will shoot laser arrows from the walls of the tower, which will cause 3 units of damage on each side. You need to keep the zombies away from the tower so they don't destroy it. To survive one day, you need to survive 5 waves of zombie attacks.