Boss bloons

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.

All boss bloons are MOAB-class and increase in health depending on the level being played.

The Vortex   Dreadbloon    Bloonarius    Blastappopoulous

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, exceptingAbsolute Zero on BMC Mobile.
 * They all move very slowly.
 * They have three "skulls", which make the given boss activate its strengthened ability. For Bloonarius, it will release a bloon ranging from Lead to ZOMG. If Vortex degrades partially, it will unleash a pulse of energy that stuns all towers around it. After every time Dreadbloon degrades, it will shield itself with yellow rocks. During each degrade of Blastapopoulos it will throw more fireballs, increasing in effectiveness depending on the number of "skulls". Each "skull" is activated when the boss reaches 3/4 health, 1/2 health and 1/4 health.
 * They are vulnerable to Boss Abilities, which include Boss Chill, Boss Bane, Boss Blast and Boss Weaken. However, they cost 30.
 * Most Anti-MOAB abilities are not as effective or is ineffective against any boss bloon. This includes MOAB Assassin only inflicting 750 damage, Monkey Pirates and Super Wide Funnel not being effective, Ground Zerodoing only 350 damage, First Strike Capability only partially reducing the boss's health, Pop and Awe andSabotage Supply Lines not having any disability effect, etc.
 * However, Absolute Zero and Pop and Awe effects do work in the Mobile version, with Pop and Awe stunning Boss Bloons for about half a second.
 * 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).
 * 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. The second attempt for any level costs  dollars, and every one after is the price of the previous. (so at level 1, $100, then $400, then $1600, etc.)

Rewards
Defeating any boss at a specific level will give rewards. 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 (100x +150) City Cash and 5.