The Hidden Tesla is a defensive building with a twist: Similar to a Spring Trap or Bomb, it stays hidden and appears when a ground or air unit gets close, or when 51% of the base is destroyed. However, unlike a Trap, it does not have to be rearmed after being deployed.
The Hidden Tesla is unlocked at Town Hall level 7.
A major source of confusion regarding the Hidden Tesla is that while it has a range of 7, it has a trigger range of 6. The Hidden Tesla will not appear unless the enemy units come within its 6-tile trigger range. The only exception to this rule is that Hidden Teslas will reveal themselves once a base has incurred at least 51% damage, as they must be destroyed (along with all other buildings) in order to achieve 3 stars.
Once the Hidden Tesla is revealed, it will stay visible and attack units out to its maximum range of 7 tiles until it is destroyed.
The Tesla deals double damage to P.E.K.K.As and prioritizes them over other troops within its range.