Boss Bloon

Boss Bloons are bloons exclusive to Boss Battle events. All boss bloons are MOAB-class and have variable number of hits depending on their level. Their level rises depending on the number of times the player has defeated them during a specific event during a specific period of time. Each boss bloon appears in a distinct track, each with variable amounts of land, water, unplaceable land, and variable path length.

In BMC Bosses change in weekly rotation over the course of entire month, Starting from: Dreadbloon -> Bloonarius -> Vortex -> Blastapopoulos.

In an update in May 2016, it is possible to play Boss Battles in BTD5 Mobile in a similar style to what is done in Bloons Monkey City. They appear first on beginner maps, and after being defeated a certain number of times will move to intermediate maps. Whether they move to advanced or expert maps and whether it follows a cycle or is random is not yet known.

The addition of Boss Bloons to BTD6 was teased on 22 July 2021, in this tweet. Later, Boss Bloons have been released in Bloons TD 6, starting with Bloonarius. The second Boss Bloon to be released in BTD6 was teased on 28 September 2021 here. Its name was later revealed to be Gravelord Lych in this tweet.

List of Boss Bloons

 * BMC, BMC Mobile, BTD5 Mobile

Encountering
In general, Boss Bloons can only be encountered when available on Boss Bloon Events.

BMC
Starting from the time when Blastapopolous debuted, Boss Bloons swap by a week-by-week basis and are always available on all 7 days of a week on every Wednesday 8:00pm NZST. This also applies to BMC Mobile, where all Bosses debuted together.

BTD5 Mobile
TBA

BTD6
Can only be encountered on Boss Bloon Events. Generally, a Boss Bloon is randomly picked by Ninja Kiwi every week. Begins on Saturday 8:00pm NZST until Thursday 4:00pm NZST (?).

BTD5 generation games
All boss bloons are MOAB-class and increase in health depending on the level being played. Each boss has a different starting health, increase in health, speed, and physical properties, but they all have these in common:
 * They are immune to slowing or stunning by normal towers, except Absolute Zero on BMC Mobile.
 * They all move incredibly slowly similar to ZOMG (With exception of Vortex).
 * They have three phases represented by "skulls" which makes its boss activate its amplified ability. Effect in question varies for each boss. Each phase activates everytime Boss Bloon loses 25% of its health.
 * They are vulnerable to Boss Abilities, which include Boss Chill, which is only way to slow & stun, Boss Bane; only way to stall Boss Blast and Boss Weaken. However, they cost 30 each and have long cooldown before they can be used again.
 * Like ZOMG they are immune to many "Instakill" abilities (such as Monkey Pirates, First Strike Capability), but they cannot be stalled or stunned (Absolute & Ground Zero, Sabotage, Pop & Awe, Super Wide Funnel) aswell, and are resistant to MOAB Assasin Ability doing only 375 damage (1/2 it does to ZOMG).
 * They all have to be defeated within one hour of summoning them with the Bloon Beacon, which otherwise would make them return to full health and come into hiding again.
 * If they leak, the player will lose. Fortunately, the player may decide to fight against the boss again with its decreased health, but it costs City Cash to re-fight. Subsequent attempts can be calucuated by this formula: 100 * level * (attempts-1) ^ 2.

BTD6
Boss Bloons in Bloons TD 6 move much slower than most bloons and possess enormous amounts of health. Because they are both considered MOAB-class bloons and Boss Bloons, Boss Bloons are vulnerable to both extra blimp damage and extra boss damage. Boss Bloons also possess multiple health stages; triggering their "skull health" will cause them to invoke an extreme retaliation that directly threatens the monkey defense, usually by sending deadly waves of bloons. Certain bosses may have different properties and gimmicks that change its overall offense and defense, but they all do share common features with each other.

BTD6 Boss Bloons have the following features in common:


 * Boss Bloons have same immunities as BAD (stuns, slowdown, knockback, and instakills).
 * Immune to all forms of percentage damage and instant health reduction (i.e. MOAB Hex, Big Bloon Sabotage, and Grand Saboteur ability).
 * Immune to Legend of the Night black hole passive ability, meaning that leaking to a Boss Bloon will result in a game over.
 * Immune to Navarch of the Seas initiative hook ability, which unlike BAD.
 * Vulnerable to sources that deal extra boss damage, specifically Paragons.

Bloons Monkey City and Bloons Monkey City Mobile
In the first release in Flash, Boss Bloons may appear only on certain weeks. Since November 2015, when all Boss Bloons were released, each Boss Bloon was available to beat for a week every week. In Mobile, when it was released a lot later, Boss Bloons always were available every week.

During the first time the boss is available, the boss, which always starts off at Level 1, can be played for free with no Bloon Beacon required. After defeating the Level 1 Boss Bloon, the Boss Bloon will come into hiding until it is summoned by the Bloon Beacon. Once summoned, the Boss Bloon will appear for one hour before it comes back into hiding, unless it is beaten within that time in which it will be defeated and you'd be rewarded some City Cash and Bloonstones (always Level*150 and 5). The Boss Bloon subsequently becomes one level stronger every time it gets beaten, unless Boss Bloon week has expired since it will go back to Level 1 after the next Boss Bloon appears.

BTD5 Mobile
Boss events may appear on any random day for the player to have a chance to defeat a Boss Bloon in one go.

The game starts with $2000 by default on Round 25 with apopalypse mode style rounds. Rounds don't stop until the Boss Bloon is defeated or the game is lost.

If you lose, either due to running out of lives from the normal bloons or the boss leaking, the boss restarts with full health. There is no Monkey Money cost for retrying.

Bloons Monkey City and Bloons Monkey City Mobile
Defeating any boss at a specific level will give the following rewards below. It resets after every Boss Battle week is over. These rewards only apply to Bloons Monkey City and Bloons Monkey City Mobile. Rewards of City Cash and Bloonstones are given every single time the boss is beaten, being equal to (150xlevel) City Cash and 5, however, beating the boss a certain number of times rewards the following:

BTD5 Mobile
The rewards vary depending on event. Monkey Money, Special Agents, or Tokens are rewarded for defeating the boss. Unlike Bloons Monkey City and Bloons Monkey City Mobile, the boss must be defeated in one single attempt; otherwise the boss fight has to be restarted and the boss will return to full health.

Below are some of the potential rewards for beating the boss:
 * 75
 * One Monkey Farmer
 * One Tribal Turtle
 * 2

BTD6
Refer to these pages for each boss:
 * Bloonarius the Inflator (BTD6)/Gallery
 * Gravelord Lych/Gallery

Trivia

 * They all have more-or-less the same death animation. Such animation involves the boss making grumbling pain remarks, self-destruction of the boss with a series of explosions, and the other bloons being stunned and popped (disappearing on mobile).
 * Bloonarius in BTD5 generation games with 10% speed of red bloon is second-slowest bloon in Bloons TD Franchise. Bloonarius in BTD6, however, reigns the slowest possible.
 * The BTD5 Pre-Round Comment for Round 70 states that Bloons in general cannot speak. However, the Boss Bloons absolutely can speak, as evident by their death quotes in BMC.
 * This also applies to the Bloon Princess from BATTD.
 * If a hero destroys a Boss Bloon with one of their hits, they will say their domination quote as if the Boss Bloon was any other MOAB-class bloon.