Spike Factory gains special targeting priority and accelerated production at the start of each round.
~ BTD6 description

Smart Spikes (previously Directed Spikes before version 14.0) is the second upgrade of the third path for the Spike Factory. It grants quadrupled production speed to the tower for 2.5 seconds every start of each round, and allows the Spike Factory to have target priorities. The target priority is initially set to Normal, its normal target priority, but it can be changed to a unique target setting to make best use of this upgrade.

It costs $340 on Easy, $400 on Medium, $430 on Hard, and $480 on Impoppable.


  • Normal: Places spikes like a normal Spike Factory.
  • Close: Places spikes at the track part(s) nearest to the Spike Factory.
  • Far: Places the spikes on the track part(s) the least close to the Spike Factory
  • Smart: Attacks bloons in the most "optimal" position possible by dispersing spikes directed at the bloon that the Spike Factory considers "optimizes" its power. By default, it places spikes as close to the applicable entrance(s) as possible. Also allows it to chase down approaching bloons easier. Otherwise, it places the spikes as most close to the entrance as possible if no bloons are detected within its radius.


  • This upgrade is useful for specifically placing spikes along specified points, particularly so for targeting onto intersection points.
    • Avoid using the Normal targeting option unless it is to roughly determine the spike pile load.
    • Use the Close targeting option for maps where there are closeby intersections, such as on Chutes, Rake, and High Finance. Close targeting is also very useful for letting the Spike Factory distribute spikes as close towards the end of the track as possible while at the same time avoiding contact from other lanes, particularly on maps such as Firing Range, Haunted, or KartsNDarts.
    • Use the Far targeting option for maps where there are far away intersections, such as on Adora's Temple, Spring Spring, or Infernal.
    • Using the Smart targeting option is a great option for anti-stalling, as it allows the Spike Factory to actively attack towards the most frontmost bloon within range.
  • The brief 4x attack speed for 2.5s at the start of each round becomes handy for preparing against fast bloons.
  • Take care when using target priorities if the Spike Factory is influenced by range buffs such as from Monkey Village or Alchemist brews. Try testing on Sandbox Mode for where the spikes may end up on certain target priorities when certain range buffs are added for the Spike Factory.


Smart Spikes is a rather situational but also useful upgrade to pick for the Spike Factory, as it sacrifices either stronger spike piles (Path 1) or faster production (Path 2) for special targeting of spikes. On most situations, random targeting is sufficient for the Spike Factory to produce maximized spike production, in order to stockpile spike piles everywhere within the tower's radius. However, there are few situations where it would be worth sacrificing one of the paths for allowance of specialized but limited custom spike pile placement. Places where there are multiple paths or intersections on the map are generally wise choices to crosspath a Spike Factory with Smart Spikes.

Along with crosspathing to Smart Spikes, there is the opportunity to further upgrade to Long Life Spikes to make even better use of Smart Spikes. When pursuing further towards Path 3, stockpiling because even more vital for optimizing its performance. Learning the ways of stockpiling spikes effectively is especially important for the final upgrade Perma-Spike.

Before considering purchasing Smart Spikes, consider if it's possible to maximize the potential of a Spike Factory without Smart Spikes. It is worth analyzing the map if it is possible to avoid overscattering of the spike piles due to multiple paths. If so, it is better off going for just Path 1 and Path 2, unless going for Perma-Spike. When setting up the Spike Factory with Smart Spikes, provided that prior Spike Factory optimization analysis was done, consider a spot where the Spike Factory should be able to dispense spike piles specifically at. Intersections are generally the best choices for Smart Spikes to go for, as they will overcome the other Spike Factory weaknesses the most.

The one other factor to note for the Smart Spikes upgrade is how this upgrade generates a brief production speed increase for 2.5 seconds before the start of each round. This can be handy in a very few scenarios, such as whenever there are many fast bloons at the start of each round. For most occasions, though, this upgrade mechanic is fairly small in comparison to the other Spike Factory crosspaths.

Update HistoryEdit


Change balloon Directed Spikes renamed to Smart Spikes

Buff Tower gains quadrupled production speed for the first 2.5 seconds of each round.



  • This upgrade is the only target-granting upgrade in BTD6 that will not automatically set one of the new target settings.
  • The "Smart" target setting is disputed in how "intelligent" the setting is. Some players even say that some of the functions in the "Smart" target setting send spikes at the worst position if the factory is already in a bad position.
  • The "Smart" target setting can detect incoming camos, as indicated by the fact that it will still stockpile spikes on the path of anticipating camo bloons, as if the camo bloons were normal bloons. This is in spite of the Spike Factory not yet counting as camo detection range for the Monkey Sub's Advanced Intel upgrade.
  • Internally, the upgrade icon's filename for Smart Spikes uses the old name as part of its filename: "DirectedSpikesUpgradeIcon.png".
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