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The Thunder Spears (雷槍 Raisō?) are a new technology specifically developed to fight against the Armored Titan. Referred to as "iron rods" by Eren Yeager, their official name is Thunder Spears, due to their spear-like shape and the thunderous sound they make when used.
The Thunder Spears are based on the technology developed by the Military Police for use against the Survey Corps. This technology was reused and applied to design a new special weapon for use against the Armored Titan. It works in a similar fashion as the anti-personnel vertical maneuvering equipment's guns and hooks, but with a strong spear loaded with explosives designed to shatter armor.
These weapons work as a two-stage rocket: an initial charge launches the projectile by pressing a special trigger in the handle of the device. The projectile, connected by a rope to the main engine, is launched with enough power to penetrate hardened Titan skin. However, when that rope is cut, the second charge is activated. This causes a tremendous explosion which makes the projectile penetrate even more into the target. Usually one was carried on each arm but up to four can be carried with proper modification to the vertical maneuver gear.
Usage and LimitationsThe Thunder Spears are a weapon which enables a human team to efficiently launch a surprise attack against the Armored Titan. But this weapon plays the role of a double-edged sword, as it is a danger to its user as well as the Titan. So much so, that it is only useful in a specific type of situation where after use, immediate retreat to close structures via vertical equipment is possible. Without a proper surrounding, the user is easily liable to get caught in the explosion. While it is also capable of damaging other types of Titans, its sole purpose was originally to kill Reiner, the Armored Titan.
Later, they were used as anti-Titan and anti-fortification weapons against the War Hammer Titan, and the Anti-Titan artillery that the Marley military acquired from their war with the Mid-East Allied Forces.
In preparation for defeating the Armored Titan, Squad Levi did not have much time to train, but Hange carefully placed her troops so that they would be in an optimal position to attack. It is a maneuver that requires three successive attacks: the first to blind the target, the second to break the protective shell, and the third one to kill.