Devastatingly large explosions, and each pops though 5 layers of bloon
~ BTD5 description
Devastating explosions pop 5 layers of bloon.
~ BTD6 description

The Big One is the final upgrade of the path 1 for the Mortar Tower in BTD5. It makes devastatingly large explosions, each popping up to 100 bloons and tearing through 5 layers of Bloons, including Black Bloons. In BTD5, it costs $10,000 on Medium.

In BTD6, the upgrade returns as the fourth upgrade of Path 1 for the Mortar Monkey. Similar to in BTD5, the attack now pops Black Bloons. Each main explosion emits an additional secondary explosion (from the Shell Shock upgrade) that can either stun non-MOAB-class bloons near the explosion epicenter for 0.5 seconds or deal 1 damage to bloons caught in the perimeters of the blast radius. Similar to in BTD5, the main explosions can pop up to 5 layers of bloons per hit and can damage bloons with Black Bloon properties. The pop limit of each explosion is now up to 85 bloons from 45 from Shell Shock. In BTD6, it costs $6,800 on Easy, $8,000 on Medium, $8640 on Hard and $9,600 on Impoppable. The cumulative cost of a 400 Mortar is $11000 on Medium, and $11880 on Hard.


  • If the player buys this upgrade with Burny Stuff for both Mortar Towers on the Direct Assault mission just before round 23, they can pass the mission without spending a single dollar in Monkey Money.
  • This upgrade isn't really effective on MOAB-Class Bloons, as it is like a slow-firing high pierce tower

BTD BattlesEdit

  • On BTD Battles, this can be used for defending a strong bloon rush, although other cheaper strategies exist.
  • Note that by itself this tower cannot pop Camo Bloons, so use this with a x/3 Mortar Tower if the opponent sends Camos.


  • The Big One is a great option for midgame due to its cheap price. It is mainly specialised against bloons, and tends to be good on Rounds like 63, 76 and 78.
    • Due to its bloon specialisation it is highly recommended to bring other DPS with decent MOAB popping power such as Arcane Spike or Quincy.
  • During Round 81+, when superceramics begin to spawn, it stops being a solo DPS tower. While retaining alright damage its role shifts towards that of stalling superceramics with its stun.
  • Infinite range, being able to negate Line of Sight, and manoeuvrability are some notable benefits of using The Big One. It benefits especially on maps with large rounded bends such as Moon Landing or Spillway.

Update HistoryEdit

Update History (Bloons TD Battles Mobile)Edit


Buff The Big One price decreased ($10000 → $6000).


Nerf The Big One price increased ($6000 → $7500).

Update History (BTD6)Edit


Buff The Big One cost reduced ($10k --> $8k)

Buff The Big One blast radius increased

Buff The Big One will now (correctly) damage DDTs when given camo detection.





  • In the Mobile version, the description originally read "Devastating explosions each pop 3 layers of bloon." (even though it still popped 5 layers). It appears that the description had an error in it. In an update, it has been corrected to 5 layers. This error still exists on the Steam version.
  • These are useful for making the game lag less because of how large the explosions are, with the huge range along with the fact that they take out more bloons instantly.
  • If the player adjusts the aim for a Mortar Tower with The Big One on the center of Mt. Magma, or the center of 3 Times Around's circle, or the center of Country Road's circle, or the center of Snowflake's snowflake, it will cover the entire circular/pentagonal center.
  • This is the only upgrade to increase the popping power of Mortars. Every other Mortar upgrade has a popping power of 40, while The Big One has a popping power of 100 (in addition to popping 5 layers, meaning the Big One can pop up to 3,100 bloons in a single shot (if it hits 100 Ceramics with 1 HP left).
  • The monkey next to The Big One seems to wear the same clothes as a Glue Hose Glue Gunner, but the cloth is protecting the monkey from radioactive mortar shells and not from glue.
  • According to the upgrade picture, The Big One cannot safely be touched by the monkeys (even with gloves) without the help of tongs to insert the mortar. However the monkey is not using them in-game, so the upgrade picture could be purely for emphasis to show how dangerous The Big One is.
  • The explosion sizes are of the same of the missiles fired by a Temple of the Monkey God, which are also as big as the radius of an unupgraded Super Monkey.
  • The Big One is one of the few explosive towers that can pop Black and Zebra Bloons, the other ones being Bloon Impact, Hydra Rocket Pods, Spiked Mines, and Flash Bomb. This is because they use Bloontonium.
  • The name may have come from the NASCAR term The Big One, meaning a huge crash.
  • It takes 40 explosions to pop a M.O.A.B's outer layer using this upgrade.
  • In BTD5 Flash, it makes a louder blast sound when its upgraded to this.


  • The artwork for The Big One does not feature the radioactive symbol on the thick mortar barrel, but the in-game tower does.
  • In the game's files, the upgrade icon for The Biggest One is named "TheBIgOneUpgradeIcon.png" with a capital I.
  • The Big One's secondary shockwave explosions can pop Black Bloons regardless of upgrades.
  • The Big One, as well as Shell Shock and The Biggest One, cannot stun Black or Zebra bloons regardless of whether it can pop them or not. It can still stun the children if the bloon was popped by the main blast.
  • The stun can affect bloons that weren't damaged due to the pierce cap, however the stun still has its own pierce cap.

Start a Discussion Discussions about The Big One

  • The Big One vs Cluster Bombs

    3 messages
    • cluster bombs maybe
    • As a “radius” goes, it is the Big One, as Cluster Bombs has some gaps in its “radius.” The Cluster Bombs and the Big One have a simi...
  • How the MOAB Assassin really works

    15 messages
    • wrote: "Facepalm" 1.3 grammar mistakes Please don't harass other people's grammar.
    • they can pop camos. They o not nee signal flare. That or I tend to use fully upgrade monkey villages too much. And grammar Nazis can screw off
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