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Ultra-Overclocked Monkeys gain a small but permanent boost every time they are overclocked.
~ In-game description

Ultraboost is the 5th upgrade on Path 2 for the Engineer Monkey in Bloons TD 6. It replaces the Overclock ability with the Ultraboost ability, which now adds a ~4.14% permanent "Ultra Charge" attack speed boost to the targeted tower (reduces attack cooldown by 4%). This special attack speed bonus can stack additively up to 10 times, and grants ~66.7% attack speed to the target tower when maximized (40% attack cooldown reduction). The permanent boost and the Overclock boosting are different bonuses, meaning that they are not calculated together. Cooldown for the ability is 35 seconds, 10 seconds less compared to its predecessor, initial cooldown is reduced to just 5 seconds instead of 15, and is capped at 3 uses per round. Duration no longer decreases at T4 and T5 towers, or Level 16+ Heroes; its ordinary Overclock buff lasts for 60 seconds on all targeted towers.

When an Ultraboost is applied to the Monkey Village, the Monkey Village instead gains a +2.5% range buff per Ultra Charge, up to +25% permanent range increase. For Banana Farms, they will produce at least +66.7% more bananas per round.

Alongside the new ability, the Engineer's nailgun's pierce is increased by +15 (from 15 to 30), and foam pierce from 15 to 30.

This upgrade costs $61,200 on Easy, $72,000 on Medium, $77,760 on Hard, and $86,400 on Impoppable.



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Ultraboost equips the Engineer Monkey with a high-tech visor and an electricity-powered resource generator on its back. Similar to Overclock, the nailgun is actually a technologically advanced gun connected to its backpack generator. The Engineer no longer wears a pencil on its ear, but instead wears ear protection that comes from its high-tech visor. The monkey also wears shoes.

The Ultraboost's Overclock ability and a normal Overclock ability cannot stack despite being depicted in the tower buffs when selecting the tower. The visual effect is the ability applied later.

Besides an additional Ultra Charge provided from the Ultraboost (plus additional extra range for Monkey Villages), similar rules regarding the Ultraboost's Overclock ability are shared with Overclock:

  • Overclocked monkeys gain ~66.7% attack speed (40% attack cooldown reduction).
  • Overclocked monkeys receive permanent ~4.14% attack speed (4% attack cooldown reduction), stacks up to 10 times.
  • Overclocked Monkey Villages gain 25% range during the Overclock boost.
  • Overclocked Villages gain permanent +2.5% range, stacks up to 10 times.
  • Overclocked monkeys will be Overclocked for 60 seconds. (171% uptime)
  • Banana Farms increase income production by at least ~66.7% during the round if Overclocked, regardless of cost of the Banana Farm being Overclocked, as their attack speeds are essentially the rate at which they produce bananas.
  • Cooldown of 35 seconds upon usage, rather than 45 seconds.

Activated Abilities[]

See also: Activated Abilities (BTD6)#Ultraboost

Ultraboost Ability

The Ultraboost ability replaces its standard Overclock ability. In addition to an enhanced Overclock effect that always boosts the tower for 60 seconds no matter the tier, a targeted Ultraboost buff also gives a permanent +6.67% attack speed, plus +2.5% range for Villages and +6.67% more bananas from Farms. A single tower can have up to 10 permanent Ultraboost stacks. To minimize the effectiveness of max-stalling for permanent Ultraboost stacks, this ability caps at 3 per round. It has a cooldown of 35s, with an initial cooldown of 5s due to the operation of decreased cooldowns of previous abilities.

Additionally, as it is an instant ability, it can be used immediately if its cooldown is reset.

The Ultraboost Ability can gain reduced cooldowns from GlobalAbilityCooldownsIcon Global Ability Cooldowns (Monkey Knowledge), Abilitized (Relic Knowledge), and the global Energizer buff. Its ability can be reset with Geraldo's Rejuv Potion.

Targeting Priorities[]

Ultraboost targets bloons using the standard targeting priorities. It shoots straight movement projectiles.

  • First: Targets the first bloon visible within its range.
  • Last: Targets the last bloon visible within its range.
  • Close: Targets the closest bloon visible within its range.
  • Strong: Targets the strongest bloon visible within its range.


Updated as of Version 43.0. Listed prices exclude external buffs, any sacrifices, and Monkey Knowledge.
[Module | Data] Purchase Sell
Costs Easy Medium Hard Impoppable Easy Medium Hard Impoppable
Upgrade (X-5-X) $61,200 $72,000 $77,760 $86,400 -
Total (0-5-0) $74,240 $87,350 $94,340 $104,820 $51,968 $61,145 $66,038 $73,374
Crosspath (1-5-0) $74,665 $87,850 $94,880 $105,420 $52,266 $61,495 $66,416 $73,794
Crosspath (2-5-0) $75,005 $88,250 $95,310 $105,900 $52,504 $61,775 $66,717 $74,130
Crosspath (0-5-1) $74,620 $87,800 $94,825 $105,360 $52,234 $61,460 $66,378 $73,752
Crosspath (0-5-2) $74,805 $88,020 $95,060 $105,625 $52,364 $61,614 $66,542 $73,938

This upgrade's prices (or included crosspath's prices) are affected by the following MK: BetterSellDealsIcon Better Sell Deals



Ultraboost is the most expensive buffing tower in the entire game, excluding Support Sacrifice Temples. It is a greatly improved version of Overclock that adds small permanent attack speed boosts to the selected tower every time the ability is activated onto said tower. It is pretty weak by itself, but its greatest value comes from maximum stacking for the long-term, most benefiting in the late end-game (Rounds 101+) when applied to the strongest DPS towers, with particular benefit for Sun Temples and True Sun Gods.


  • As its cost is extremely high for just one support upgrade, it is better to use Ultraboost for late-game. Particularly, it is very useful on Sun Temples and True Sun Gods.
  • One Ultra Charge on a Monkey Village or a Banana Farm grants the effect of a tenth of an Overclock. The maximum 10x Ultra Charges is roughly the same as a normal Overclock on those towers. These effects are then also stackable with an Overclock effect; e.g. a farm with maximized Ultra Charge and an active Overclock will generate 4x more income per round than usual.
    • However, it seems that 10x Ultra Charge will actually grant 1 extra banana/crate drop on a farm from its already-boosted income.
  • As with Overclock, Ultraboosting a Monkeyopolis will not increase income production, but will increase its range.
  • The best crosspath for Ultraboost is not to crosspath it, unless it is for excelling mid-game. In that case, 0-5-2 is superior. Sentries from this tower deal greater damage thanks to Deconstruction, but this wastes potential for optimizing the nailgun's generous 30 pierce. Otherwise it is simply a waste of money to crosspath this tower.
  • The Ultra Charge will be applied when the tower is temporarily boosted and will persist when the temporary boost has expired.
  • Adding Energizer will decrease Ultraboost's cooldown to 28 seconds, allowing it to keep up to two Tier 5 towers overclocked indefinitely with full uptime.
  • Beware that Ultraboost has a cap of 3 uses per round for a single tower, so it is bad idea to leave it lingering on the map if all planned towers are already got full Ultraboost stacks.
  • Selling an Ultraboost won't remove its permastacks, unlike Permanent Brew.

Version History[]

Balance Changes[]

While still the most powerful but expensive support upgrade in the entire game outside of Support Temples, Ultraboost had gained some nerfs and buffs, but overall has been slightly nerfed. Slight cooldown decrease and Ultra Charge application rework arguably are simply quality-of-life changes for this upgrade, and the main attack buff is negligible in late-game scenarios. Price decrease does buff its viability but only realistically to edge its viable purchase on CHIMPS games. Version 35.0 reduced its price by large amount to be more accesible.

  • NERF Ultraboost attack speed boost reduced (100% → ~66.7%).
  • NERF Ultra Charge attack cooldown reduction lowered (5% → 4%, up to ~66.7% attack speed permanent boost instead of 100%).
Continuing our efforts to make crosspaths meaningful and fit the style of each path more solidly, a number of crosspath and base level balance shifts were made.
~ Ninja Kiwi
  • BUFF Ultraboost will now apply Ultra Charges upon ability activation rather than expiration.
  • BUFF Ultraboost's regular Overclock effect's ability buff state will now be included in save files.
Engineer is quite poor in terms of crosspathing, so we've added crosspath benefits to Cleansing Foam as well as an overall price buff to the middle crosspathing upgrades. We've been somewhat unhappy with how Overclock sits in the game for a while and especially how the interaction with tower cost causes levelling heroes naturally to be far advantageous over purchasing upgrades when this is already underused. We have made an attempt to rework these issues by moving it to a tier-based system rather than price.
~ Ninja Kiwi
  • BUFF Affected by Cleansing Foam crosspathing benefits
  • Change Reworked duration of Ultraboost's Overclock effect, due to rework for Overclock.
[...] We've added a pierce & speed boost to Overclock's base upgrade and lowered the cooldown on Ultraboost to allow the possibility for it to achieve full uptime as a freeplay tower and get its stacks up faster. [...]
~ Ninja Kiwi
  • BUFF Ultraboost's main attack's projectile speed increased (375 → 750).
  • BUFF Ultraboost's main attack's pierce increased (3 → 30).
  • BUFF Ultraboost ability cooldown reduced (45s → 35s).
  • BUFF [Undocumented] Ultraboost ability initial cooldown reduced (15s → 5s).
  • BUFF Affected by smarter Cleansing Foam buff
[...] Cleansing Foam has had some extra crosspath utility added at the cost of a small price increase and a large decrease to Ultraboost price.
~ Ninja Kiwi
  • BUFF Ultraboost cost decreased ($120,000 → $105,000)
  • BUFF Affected by improved Cleansing Foam crosspathing interactions
Yes, Ultraboost had to be changed for now in response to exploits. Not a fan of that either and will be looking for a better long term solution, but it was 'the' change that could easily be made with no risk and there are far more important things to put our time into fixing right now.
~ Rohan, Version 32.1 comment
  • NERF Ultraboost ability is now capped at 3 uses per round
Cleansing Foam is only seeing a slight tweak to help it be more viable if you want to attempt it as 'main camo detection’, and this mainly fixes some issues in ABR games allowing it to catch quick initial camo spawns.
~ Ninja Kiwi, referring to Cleansing Foam
  • BUFF Affected by Cleansing foam buffs
Overclock's considerable longer duration benefit on lower tiers currently serves little purpose and only leads to weirdness in upgrading boosted towers, so for now we’d rather minimize this on the early cases that don’t serve much purpose.
~ Ninja Kiwi, referring to Overclock
  • NERF Ultraboost now no longer has longer ability duration for below T3 tower or Level 12 Hero
    • Ultraboost buff to T0 reduced 1.75x → 1x
    • Ultraboost buff to T1 reduced 1.5x → 1x
    • Ultraboost buff to T2 reduced 1.25x → 1x
[...] Engineer Ultraboost is limited to viable use in high-farming situations due to its cost, and while the buff is great when applied to strong towers, we find it too expensive for an upgrade that only adds a buff to other towers, especially in games where cost is the primary focus.
~ Ninja Kiwi
  • BUFF Ultraboost price reduced $105,000 → $72,000
  • BUFF [undocumented] Ultraboost can no longer target upgraded Beast Handlers that lack any beast
  • NERF [undocumented] Ultraboost can no longer target or affect Beast Handler's birds
    • Note: Ninja Kiwi incorrectly addressed "5-x-x & x-5-x Beast handler paths are now overclockable", which implies that beasts from Paths 1 and 2 can be buffed from Overclock; from testing, the actual balance change is that birds no longer accept Overclock or Ultraboost buffs, and previously all Beast Handlers could accept the Overclock buff properly and pass them to their beasts, just now water beasts can accept the buff better by increasing rate of the splash.
[...] Some minor QoL buffs for Ultraboost as it's very expensive over multiple T4s. [...]
~ Ninja Kiwi
  • BUFF Ultraboost cleansing foam pierce increased from 10 to 30
  • BUFF Ultraboost ability now has full duration on T4s, duration increased from 45s to 60s
  • BUFF Ultraboost ability now has full duration on T5s, duration increased from 30s to 60s

Bug Fixes and General Changes[]

  • Change Description changed from "Overclocked Monkeys gain a small but permanent boost each time Overclock wears off." to "Ultra-Overclocked Monkeys gain a small but permanent boost every time they are overclocked."

Extra Notes (Version History)[]


When deploying Cleansing Foam:

When activating Ultraboost Ability:


Official artwork[]


  • When it was first released, Ultraboost was the fourth-most expensive upgrade in the game, costing $120,000 on Medium, which was tied with Flying Fortress at the time, followed by Super Mines, Legend of the Night, and True Sun God. Version 22.0 reduced the price of Flying Fortress, making Ultraboost the fourth most expensive. Following a massive price reduction to Ultraboost in Version 35.0, many upgrades overtook it as the most expensive non-Paragon upgrades.
  • Before Version 18.0, Ultraboost was the most expensive upgrade to be purchasable on CHIMPS Mode before Round 100. This feat was first achieved by a user who was attempting this on Logs CHIMPS.
    • The first recorded instance of Ultraboost purchased in CHIMPS was done on September 23rd 2019.[1]
  • Until Version 16.0, Ultraboost could be linked to a Tech Bot, but not for Overclock. For both Ultraboost and the later Overclock, applying Tech Bot onto either will automatically reuse its ability on the previously targeted tower.
  • Similar to Overclock, Version 14.0's official patch notes has an error regarding the Ultraboost attack speed boost nerf. The nerfed attack speed boost was actually from +100% to +66% instead of to +80%, and the Ultra Charges are decreased from +10% to +6.66%; this mistake is likely due to a confusion between the concepts of attack cooldown (i.e. for the multiplicative increase/decrease for an attack per unit time) and attack speed (i.e. for the percentage increase/decrease for the numbers of attacks per second).[2]