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Erosion is an Advanced Map in Bloons TD 6. It was announced on April 11, 2022, as one of three joint winners of the 200k Map Concept Competition, along with Dark Dungeons and Covered Garden. It was originally designed by TheWiseTroll.

It was added in update 37.0 on June 7, 2023, alongside the Magus Perfectus.

Overview[]

The map takes place on a slowly eroding large ice platform that melts into the Arctic Ocean. Starting from Round 18, this ice slowly erodes away every 18 rounds, revealing oceanic water where water towers may be placed, repeating up to 5 times. The bloons move along the margin between the ice and the sea, which moves gradually from the bottom left to the top right of the map each round as the rounds progress up to Round 90, after which the erosion will make no more progress. By that point, the only natural land remaining is the glacier in the top-right corner, which can only fit a very limited amount of towers.

The Rounds where the land erodes are 18, 36, 54, 72 and 90. Past round 90 there is no more erosion. Rounds beyond 90 and before round 18 have a track length similar to the map Blons. Every time the erosion rounds hit, the polar bear quickly jumps to the next available land on the right as it escapes the immediate land erosion. Additionally, the polar bear is just a creature; it cannot block Line of Sight, and does not affect tower placement.

Any land-only towers that end up in the water due to the erosion will be sold. Amphibious units such as Pat Fusty and Sun Temples are floated into the water instead, making them now count as water towers if previously placed on eroded ice.

The glacier is the only land spot that isn’t affected by Erosion’s land erosion. It artificially cannot fit a Heli Pilot despite having a smaller footprint than Banana Farm, but can barely fit a Banana Farm. It also has enough room to fit up to 3 Monkey Villages.

Path Structure[]

Erosion is unique in that it has multiple unused lanes that are reserved only for specific periods of rounds. More specifically, the bottom-most lane is only used for Rounds 1-17, followed by 18-35, 36-53, 54-71, 72-89, and 90+ at the top-most lane. Because of this, towers that depend on unused lanes, such as 0-4-2 Spike Storm and Beast Handler's birds, can benefit on Erosion.

Strategy[]

Main article: Erosion/Strategies

Summary[]

Erosion has the major challenge of slowly degrading sea ice over rounds, which is especially problematic without the use of towers with self-mobile footprints such as Dark Knight, Corvus at level 7, the Support Chinook's Redeploy ability, frozen water platforms from multiple Arctic Winds, or waterborne land supporters such as Carrier Flagship and Navarch of the Seas. Use early rounds to add "disposable" towers, and follow up with defenses that take advantage of water or low-footprint long range as rounds go by. In non-CHIMPS gameplay, Arctic Winds can be used to fully prevent land towers from drowning; at least two Arctic Wind platforms on the water are needed to prevent water-placed land towers from drowning, requiring a total of an extra one Arctic Wind (minimum of three) to support land towers fully.

The general guideline for Erosion is to invest for long-term, long-ranged defense with low footprint, especially Sniper-focused setups with water towers along the way. A general early-game would be to do a Sub start into Sniper, followed by some fairly disposable towers and a high-utility hero such as Geraldo. For mid-game and following up into late-game, build the defense on small-footprinted long-ranged towers. Water can be utilized for building up water-focused utility.

For gameplay outside of Half Cash and CHIMPS, a heavy investment in Merchantmen farming would be one of the more effective ways to farm alongside multiple Farms prior to the first Merchantman. Arctic Wind ice platforms to "terraform" water can be done by using two waterborne Arctic Winds in range of each other and a third Arctic Wind to bridge the land into water for the other Arctic Winds. From there, the player may expand their income and defenses to overcome the extremely short lanes coming into late-game.

In CHIMPS, this can be a little tricky. Use as minimal early-game spending as possible, and don't fear to use a few 0-0-0 Darts to help out along the way. Utility heroes with long-ranged potential are generally best preferred, particularly Geraldo and his shop, with many other hero choices lacking either utility or long range throughout all stages of the game. Long-ranged water towers such as 2-0-2 Airburst Darts, and long-ranged land towers such as 1-3-0 Druid of the Jungle, 4-2-0 Maim MOAB, and Bouncing Bullet may be helpful to get through the early-to-mid-game. Late-game CHIMPS usually consists of at least one Village alongside a late-game exit protector such as Perma-Spike and several general supporting options that minimize high density bloon problems, such as Arctic Wind and MOAB Press.

Tips[]

  • Erosion’s glacier does not allow a Heli Pilot, making it impossible to make it survive without sea ice platforms. Banana Farms can barely be placed, but only one can fit.
  • There is enough space on the glacier for three Villages, although using only one Village is recommended if exclusively using the glacier. Call To Arms may be helpful, given such the low space for land towers that a strong support option is needed.
  • 0-4-2 Spike Storm is an excellent choice for the Round 100 BAD, as the incredibly short lane in Rounds 90+ counts as the only active lane, allowing the spikes to utilise maximum pierce against the BAD. Other Spike Storm crosspaths aren’t recommended, as they’ll waste spikes on the other five lanes.
  • Though this may not seem like it at first, Sauda is a great starting tower. She can solo the whole 17 rounds, can save up enough money for a Druid of the Jungle, and can easily be sacrificed for a low cost before the first erosion. This is doable also on CHIMPS, though placement, appropriately-timed ability, and frankly a bit of luck are factors to consider when attempting.

Sounds[]

When ice erodes:

Gallery[]

Concept Art[]

Map States[]

Trivia[]

  • TheWiseTroll was uncertain on how the map on rounds beyond Round 100 operates. Initially he intended for the water to no longer move after that round, but he also allowed for the possibility of the water retreating back to its starting position up until Round 200, after which the cycle restarts again. The final design was to make the water remain after Round 100, after redesigning the map as an Arctic ice platform.
  • The original design of this map was intended to be set on a beach with increasing levels of water, later finalized by Ninja Kiwi into an Arctic theme. This makes Erosion the first community map with substantial thematic changes compared to the original design.
  • Erosion CHIMPS was first declared completed on r/btd6 by Chom Chom, who posted his completion with Snipers in a corner. Link.
  • This map may possibly insinuate global warming or glacier melting news in real life time.
  • Erosion isn’t the only map that has an artificial blacklist of specific tower types without involving specific tower classes. Another example is Spillway’s barrel, which artificially can only fit small footprint towers so that only these types can neatly fit inside.


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