The formation of the seven books was extended to a number of seven formations that were higher than the six because of the addition of other new defensive buildings, so that the original formation was no longer applicable. The double-back formation is one of them, through the clever arrangement of the anti-aircraft lineup and built-in traps to make the attack of this formation very difficult, but also let this formation have enough space to reserve traps, further increasing the difficulty of enemy conquest.
The entire formation is in two loops, overlapping and intersecting with each other, and the center of the formation leaves a large number of open spaces, which can be used to place traps, which can either slow down the enemy's excessively fast destruction speed, or exchange virtual and real, so that the enemy cannot see the virtual reality.
The interior of the formation is arranged with the base camp as the core, supplemented by giant cannons and multi-barrel mortars, while taking into account both individual and group damage.
A series of defensive buildings built around the central open space of the formation are respectively rock-shaking boulders, lava cannons and multi-barrel cannons, and the health of the rocks is very strong compared to other defensive buildings, which can withstand a lot of damage, but it should be noted that around the formation, it is supplemented by long-range defense buildings such as arrow towers to ensure the perfection of the formation's defense circle.
The position of this formation piggy bank is very cleverly placed, because in the night world, the piggy bank is not a very important defensive building, and it is most suitable to protect the more important defensive building and attract enemy fire.
It is a very good choice to distance the wall from the defensive building, which can either block the enemy's attack for the first time, or let the defensive buildings within the city wall have enough time to output damage to minimize their own losses.