Look out! Here comes a group of powerful bloons that might overwhelm your monkeys! Use Monkey Boost to speed up all of your Monkeys for 10 seconds.
~ Quote appearing when a dense rush of Pink Bloons appears.
Use Monkey Boost to temporarily speed boost all your monkeys. ...
~ Part of a quote after starting a track from My Tracks
Let's turn it up to 11! All monkeys attack twice as fast for 15 seconds.
~ Description on the BTD6 Powers page
Monkey Boost (or Tower Boost in Bloons TD Battles Mobile) is a boost in Bloons Monkey City, Bloons TD Battles Mobile and Bloons TD 6 that doubles the attack speed of all towers on screen for 10 seconds. To purchase this, the player must pay 5 in Bloons Monkey City (10 on mobile), 1 in Bloons TD Battles Mobile or 100 in BTD6. To prevent Monkey Boosts from stacking, this boost has a cooldown like an Activated Ability and has to recharge before the player can use it again. The countdown can be decreased in Bloons TD Battles Mobile using COBRA's Monkey Stimupgrade. When it is received as a bounty from the Monkey Knowledge Packs in Bloons Monkey City, you receive 5 free Monkey Boosts.
Use the Monkey Boost when your towers cannot defeat an incoming rush. The usage of the boost varies between towers, and it is recommended to understand the different situations in which your set up can beat with or without Monkey Boost.
Other than functioning like most other powers that allow the player to salvage a losing game, it also can be used late-game to boost your True Sun God to allow for the highest round.
Its appearance when playing a track on My Tracks
Using a Monkey Boost in BMC
Using Monkey Boost on the free dart monkeys in dire desperation
Using Monkey Boost in BTD6 (note the blue outlines on the corners of the map)