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BTD6

Unleashes regular blasts of forked lightning that arc from bloon to bloon.
~ In-game description

Heart of Thunder is the second upgrade of Path 1 for the Druid in Bloons TD 6. In addition to the hardened thorns, Heart of Thunder allows the Druid to shoot lightning bolts, similar to a 2-x Monkey Apprentice in BTD5. Unlike earlier games, which instantaneously hit a certain number of targets in a single attack, the Heart of Thunder's lightning works in a fork-by-fork basis, hitting a single target and then recursively striking 2 more bloons over brief intervals up to an extent. More specifically, it forks a single bloon which then forks up to 2 bloons per lightning bolt up to 5 times. As a result, each lightning attack can hit a total of up to 31 bloons. If a particular lightning fork fails to find a target within its seeking range, it ceases to hit more bloons.

Lightning bolts are shot every 2.3 seconds, deal 2 layer of damage, and bolts target bloons with lightning behavior when seeking new targets. Lightning seeks bloons within up to 86 units of range. These bolts also follow along the track; and when paths intersect or are near to each other, such as on Cubism, it will jump from path to path randomly zapping bloons. Lightning seems to always target bloons behind its initial target, and virtually never arcs towards bloons ahead of it.

Although the Druid's thorns keep the Normal damage type, bolts cannot affect Purple Bloons. Lightning bolts cannot increase pierce by any means but can accept any other external buff.

This upgrade costs $720 on Easy, $850 on Medium, $920 on Hard, and $1,020 on Impoppable.

Description[]

Overview[]

Placeholder other

Heart of Thunder

Adding this upgrade grants the Druid new blue headwear, as well as a carved diamond on top of its wooden staff. The wooden staff remains on the monkey's left hand. Whenever the Druid summons lighting, the monkey pushes his right hand forward to initiate the forking of lightning.

When crosspathed, all Druids up to Tier 4 receive the same new wooden staff with carved diamond. All Tier 3 and below crosspaths receive the blue headwear except for Druid of Wrath; both Tier 4 crosspaths Jungle's Bounty and Poplust do not receive full visual changes gained from Heart of Thunder.

Binary tree-1

Five-generation binary tree, a model for Heart of Thunder's lightning forking algorithm

Purchasing the Heart of Thunder upgrade grants the Druid a new lightning attack. The lightning works in the same way as how a binary tree operates; the lightning bolt hits one target then splits into 2 lightning bolts via forking. It repeats this process up to 5 times. If there is no target within 86 range of the bolt, it ceases to hit more bloons. Because of how this works, a single lightning attack hits up to 31 bloons, equal to (2^5)-1.

Heart of Thunder can accept Heart of Oak's degrow. Thorns are exactly like Hard Thorns, gaining Normal Type (pops Black, White, Purple, Lead, Frozen) Normal damage type.

Targeting Priorities[]

Heart of Thunder targets bloons using the standard targeting priorities. Its main thorn attack 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.

The initial lightning attack targets bloons based on the current targeting priority of the Druid, and forks at bloons based on an algorithm that attempts to follow a similar targeting priority. It is not certain whether lightning forking dynamically follows the Druid's targeting priorities or if lightning forking is locked on a specific targeting such as Close.

Costs[]

Updated as of Version 41.0. Listed prices exclude external buffs, any sacrifices, and Monkey Knowledge.
[Module | Data] Purchase Sell
Costs Easy Medium Hard Impoppable Easy Medium Hard Impoppable
Upgrade (2-X-X) $720 $850 $920 $1,020 -
Total (2-0-0) $1,355 $1,600 $1,730 $1,920 $949 $1,120 $1,211 $1,344
Crosspath (2-1-0) $1,565 $1,850 $2,000 $2,220 $1,096 $1,295 $1,400 $1,554
Crosspath (2-2-0) $1,860 $2,200 $2,380 $2,640 $1,302 $1,540 $1,666 $1,848
Crosspath (2-0-1) $1,440 $1,700 $1,840 $2,040 $1,008 $1,190 $1,288 $1,428
Crosspath (2-0-2) $1,695 $2,000 $2,165 $2,400 $1,187 $1,400 $1,516 $1,680

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

Strategy[]

Summary[]

Heart of Thunder works very similarly to the Monkey Apprentice's Lightning Bolt upgrade, and therefore can be used to counter Lead Bloons and large groups of bloons due to the nature and pierce of the forked lightning from far away. Since a single lightning bolt spawning numerous Pinks can overwhelm Druid, a good handful of Druids with Heart of Thunder may be necessary to optimize the grouped damage potential of this new attack. Druids can be upgraded with Heart of Oak to strip Regrow properties or gain further attack speed along Path 3 (e.g. Heart of Vengeance) to boost their grouped bloon popping potential.

Tips[]

  • This upgrade, combined with Druid of Wrath, can accelerate wrath bonuses very quickly compared to Thorn Swarm crosspaths, due to how much the pierce Heart of Thunder provides can impact large groups of bloons. Druid of Wrath's wrath bonuses are dependent on the amount of total damage dealt consecutively, assuming that the Druid of Wrath is not idle for more than 2.0s.
  • Note that the lightning bolts cannot affect Purple Bloons. There are alternative upgrades available that act similarly to Heart of Thunder and can hit Purple Bloons, including Boomerang Monkey's Glaive Ricochet and M.O.A.R. Glaives upgrades.
  • The 2-2-0 Heart of Thunder is a decent choice for removing Regrow properties off grouped Regrow Bloons, such as those on Rounds 76 or 79, due to the Heart of Oak buff in Version 18.0.

Version History[]

Balance Changes[]

Heart of Thunder itself had a slight change when it was first released, with early updates improving it slightly more, though the documentation for this was too old to be confirmable due to the game being a few weeks old at the time. Heart of Thunder, however, got buffed with the Heart of Oak interaction by allowing it to strip Regrow properties.

18.0
  • BUFF Heart of Thunder with Heart of Oak can now strip Regrow properties off bloons.
27.0
  • BUFF Avatar of Wrath's damage scaling now affects Heart of Thunder lightning as well, with it gaining +1 damage for every 6000 RBE onscreen, at a cap of +15 damage.
33.0
Top path Heart of Thunder doesn’t scale well with tiers for an upgrade with such niche use & generally feels lacking, so it is seeing general power improvements across the board to upgrades that incorporate this attack. [...]
~ Ninja Kiwi
  • BUFF Heart of Thunder lightning damage increased from 1 → 2
  • BUFF Heart of Thunder now applies full damage-scaling effects for Avatar of Wrath
37.0
[...] Avatar of wrath doubles the base attack speed before any scaling is applied, but this hasn’t ever applied to the 205 Lightning, so taking care of that as well. [...]
~ Ninja Kiwi, referring to 2-0-5 crosspath
  • BUFF Heart of Thunder lightning now gains double attack speed when given Avatar of Wrath
41.0
Hard Thorns is useful and often taken for crosspath even if not going for 2xx as lightning is comparatively very expensive for what it offers so moving Thunder's cost out into both the surrounding upgrades.
~ Ninja Kiwi
  • BUFF Heart of Thunder price reduced from $1000 to $850
    • Actual cost decrease is -$50 due to Hard Thorns costing $100 more.

Sounds[]

When striking lightning:

Gallery[]

Official artwork[]

Videos[]

Trivia[]

  • As of Version 18.0, a 2-2-0 Druid is roughly equivalent to a Rank 4+ (from Monkey Knowledge Packs) 2-0 Monkey Apprentice on Bloons Monkey City, except lightning bolts are guaranteed to remove Regrow properties instead of being capped at a 70% chance.
  • According to Ninja Kiwi's 5th November 2021 blog, Druid's lightning is based on "seeded formulaics" rather than pure RNG.
  • The forking algorithm for Heart of Thunder is the same model as a five-generation binary tree.
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