Updated for Town Hall 18 (October 2026).
The Builder Base Hidden Tesla is a 2×2 defense that stays buried and invisible until a troop comes within 6 tiles, then pops up and zaps ground and air units one at a time. You get one at Builder Hall 3, a second at Builder Hall 6 and a third at Builder Hall 7. Max level is 10 at Builder Hall 10, firing 85 damage every 0.6 seconds.
How the Hidden Tesla works
During scouting and the early part of a battle, the attacker can’t see it. It reveals itself in one of two ways: a troop moves within 6 tiles of it, or 51% of the stage it sits on has been destroyed. Once up, it hits a single target with rapid electric shots out to 7 tiles, and it stays up for the rest of the battle.
Troops that go for defenses first ignore a Hidden Tesla until it has revealed itself, even if every other defense is gone. That is why a Tesla can quietly eat the opening move of a defense-targeting troop meant for something else.
Hidden Tesla levels and stats
Costs are in Builder Gold. Times are base values before any Gold Pass builder discount.
| Level | Builder Hall needed | Damage per shot | Damage per second | Hitpoints | Cost (Builder Gold) | Upgrade time |
|---|---|---|---|---|---|---|
| 1 | 3 | 36 | 60 | 300 | 50,000 | 30m |
| 2 | 3 | 40 | 66 | 350 | 100,000 | 3h |
| 3 | 3 | 44 | 73 | 400 | 150,000 | 5h |
| 4 | 4 | 48 | 80 | 460 | 280,000 | 10h |
| 5 | 5 | 53 | 88 | 550 | 700,000 | 1d |
| 6 | 6 | 58 | 96 | 650 | 1,300,000 | 2d |
| 7 | 7 | 64 | 106 | 750 | 2,100,000 | 4d |
| 8 | 8 | 70 | 116 | 850 | 3,100,000 | 6d |
| 9 | 9 | 77 | 128 | 1,000 | 4,100,000 | 8d |
| 10 | 10 | 85 | 141 | 1,150 | 5,100,000 | 10d |
Range is 7 tiles and the trigger range 6 tiles at every level. With three of them at Builder Hall 10, maxing the set takes 50,940,000 Builder Gold.
How many Hidden Teslas you get
One at Builder Hall 3 to 5, two at Builder Hall 6, and three from Builder Hall 7 to 10. From Builder Hall 6, each stage has a defense limit (13 at Builder Hall 6 to 8, 14 at Builder Hall 9 and 10), and your Teslas count toward it, so you decide how to split them between the two stages.
Where to place Hidden Teslas
- Next to the buildings a defense-targeting troop will pass on its way in. A Boxer Giant may spend its first big punch on the Tesla, and a Hog Glider may crash into it instead of a defense that matters more.
- Near short-range buildings that a Cannon Cart in long-range mode would normally pick off from safety. The Tesla only appears once the cart is well inside its own range, and then it fights back.
- Covering an air path. At low Builder Halls, an attacker who has just taken out your Firecrackers often sends Beta Minions in, and a hidden Tesla catches them off guard.
- In a far corner on its own, as a timer trap. If the attacker has deployed everything before 51% and nothing is near it, the last few percent can take too long.
How to find and beat Hidden Teslas
Count defenses. At Builder Hall 10 a fully built base has 27 defenses and each stage holds at most 14, so every stage has at least 13. If you can see only 10 non-Tesla defenses on a stage, all three Teslas are there; if you see 14, that stage has none. This only works if the defender has built everything, but at high Builder Halls that is usually the case.
Look for gaps, too. A Tesla needs an empty 2×2 spot, and a suspicious hole in an otherwise tight layout is often one. Once it is up, it only hits one target at a time, so groups of cheap troops or a tank with support behind it take it down quickly. Its hitpoints are low for a late defense (1,150 at max).
What changed, and when
Builder Base 2.0 (May 15, 2023) made several changes:
- The second and third Teslas moved one Builder Hall earlier, to Builder Hall 6 and 7 (they used to come at 7 and 8).
- With bases split into two stages, the automatic 51% reveal now counts the Tesla’s own stage rather than the whole base.
- Its stats were rebalanced upward: a level 9 Tesla went from 91 damage per second and 840 hitpoints to 143 and 1,000.
- Level 10 was added for Builder Hall 10.
That buff was trimmed on October 20, 2023, when Supercell’s balance notes cut Builder Base Tesla damage per second by 10%. Level 9 dropped from 143 to its current 128. The Home Village Hidden Tesla is a separate building with its own levels.
Hidden Tesla FAQ
How many Hidden Teslas can you have at Builder Hall 10?
Three, the same as Builder Hall 7 to 9.
When does a Builder Base Hidden Tesla reveal itself?
When an enemy troop gets within 6 tiles, or when 51% of its stage is destroyed.
Does the Hidden Tesla hit air troops?
Yes, it targets both ground and air, one unit at a time.
Sources: Supercell, Builder Base 2.0 patch notes (May 15, 2023); Supercell, October 2023 balance changes; in-game data.
