Boss Bloon Event/BMC/Bloonarius

Overview
Bloonarius is an event in Bloons Monkey City consisting of a single battle against a boss bloon, Bloonarius the Inflator, as well as additional bloons that spawn throughout the battle. It first debuted on 6/24/15, and another event began on 7/21/15. The event lasts for 7 days and is linked to the Bloon Beacon, as defeating the Bloon Beacon tile is essential for activating the event.

To access the boss the player must defeat the tile where the beacon is located. The player then has 1 hour to battle and attempt to defeat Bloonarius. If you fail to defeat Bloonarius within that hour, it will regenerate back to full health, and the cost will reset.

Bloonarius has its own unique battle tile (though it occupies no location on the map; access is through the event tabs on the right of the screen) which appears to be a dark, nighttime swamp, laid out in a widening spiral from the starting point at the center of the map.

The player starts with 2 times the cash of a normal tile (including bonuses such as Magic Coin Purse), and supply crates also give double cash. Throughout the battle bloons will also file out of the starting point. At the top of the screen is a life bar for the boss with skulls marking 25%, 50% and 75% health. When those points are reached additional bloons are spawned at Bloonarius's current position, the difficulty depending on Bloonarius's level, including MOAB's (and higher) starting on level 5 of the encounter. The battle consists of a single round (which does appear to be subdivided into a number of actual rounds for purposes of Banana Farms, Cuddly Bear, etc.; see Strategies) and ends either when Bloonarius runs out of life (success), reaches the exit (failure), or enough lesser bloons reach the exit to take the player down to zero health (failure). However if you do fail, any damage dealt to Bloonarius will carry over to the next attempt, assuming there is sufficient time. Damaging Bloonarius does appear to generate cash.

Bloonarius has at least 25 levels (there are no additional bonus rewards after level 20 and and achievement for level 25 and, at this time, no reports of a final level to the event), with difficulty and level increasing every time it is defeated. The cooldown of Bloonarius is essentially linked to the Bloon Beacon (which has a 6 hour cool down). This means defeating twenty levels will take a minimum of 5 days plus the amount of time for each level's battle with the boss, excluding bloonstone recharges to the Bloon Beacon.

Reattempts
The initial attempt is free, however if you fail you will have to pay a fee to try again. The second and subsequent tries on Bloonarius during each 1 hour window cost cash. The amount is calculated by this formula:


 * Cost = min((Attempt_number-1) * (Attempt_number-1) * 100 * Bloonarius_level, $50000)

For example, if it takes 7 attempts to take on level 17, the attempts will cost:


 * 1st - free
 * 2nd - $1700
 * 3rd - $6800
 * 4th - $15300
 * 5th - $27200
 * 6th - $42500
 * 7th (and subsequent) - $50000

Rewards
In addition to the standard 5 and cash for each defeat, bonus rewards are given for beating the following rounds:

Unlike normal tiles, the player is not awarded bonus Bloonstones for finishing with no loss of life (NLL).

Strategies
For strategies, see Bloonarius the Inflator.