This is part of my “Pyre” world.
Shockers are man-sized metal cages with long, serpentine metal legs, which patrol a limited area for intruders. When an intruder is detected, the shocker wraps its tentacle-like legs around its enemy, drawing it towards the cage. Once the enemy is captured, the cage closes and is electrified, and the enemy is shocked into unconsciousness.
Shockers are particularly popular in the Nobles’ and Merchants’ Districts of Pyre.