Source: Numeria, Land of Fallen Stars, pg(s). 56
Arachnid robots come equipped with a plasma welding torch that resembles a scorpion's tail. They can use their claws as an additional pair of limbs when climbing.
Arachnid robots serve as sentinels, spies, and pets of Numerian technologists. Under stress, an arachnid robot's plasma core can overload and explode in a fiery blast. Because of this, they have been used as suicide bombers, but arachnid robots have a sense of self-preservation and only do so when tricked. Due to their small size, they are the easiest robots to smuggle past Technic League agents outside Numeria.