Magic Monkeys Only is one of the seperate game modes in Bloons TD 6. It is unlocked for a certain map after unlocking Standard Hard Difficulty of that respective map. As Magic Monkeys Only is found under the Hard difficulty set, it shares its penalties of 100 Lives, an increased cost for all towers and their upgrades by 8%, a late start at Round 3, and faster bloon speeds when compared to Medium Difficulty. As the name suggests, it restricts the usage of towers similar to prior game modes Primary Only and Military Only, featuring the Ninja Monkey, Wizard Monkey, Super Monkey, Alchemist, and Druid, as well as any Hero the player chooses.
Given the limitations of only 6 types of towers to utilize on top the difficult penalties that Hard poses on the player, the player must understand what each tower can provide.
Druid provides a cheap and effective early game popping power to hold off the bloons as more expensive towers can be saved up for. Mid-to-Late game requires strategies such as Poplust or using Druids as support against non-MOAB class bloons with the Path 1 upgrades and Druid of the Jungle. With the lack of farms, purchase of Jungle's Bounty is highly disadvantageous, even with its base $200.
Wizard Monkey provides a quirky but sometimes needed gimmicks to fend off the bloons, with Shimmer serving as a great general Camo denial system in the correct places and Arcane Mastery providing a decent mid-game bloon popping tower that ignores Line of Sight issues. Also, the middle path provides a cheap Lead Bloon popping power.
Ninja Monkey has an interesting role, able to provide the large bulk of the player's early-to-mid game defense as well as access to Sabotage Supply Lines. Sticky Bomb and Bloonjitsu also help to clear the denser levels of MOABs, as well as Flash Bomb helping on critical bloon rush rounds of 63, 76 and 78. Ninja Monkey is also arguably the most reliable way to beat Purple Bloons and Camo Bloons and when combined with a Berserker Brew or Obyn Greenfoot, it becomes a power bloon-popping force.
Lead to Gold can be highly utilized on Camo Lead rounds by having a x/0/3 Wizard nearby to decamo the Camo Leads without themselves popping them, allowing Lead to Gold to convert the decamoed Lead Bloons into gold for huge income profit.
Super Monkey serves as the late-game tower of choice, providing a large bulk of popping power in turn for its high costs. Combining the likes of a PlasmaRobo Monkey or an Sun Avatar with a Berserker Brew or Stronger Stimulant allows for a very powerful force (though Version 6.0 nerfed this synergy by expiring the Alchemist buffs after specified amounts of hits). A large weakness however is Purple Bloons once Laser Vision or higher is purchased, requiring another tower to pop them.
As the game mode is centered around Magic Monkeys, the hero of choice is likely to be Obyn Greenfoot, as his bonus of increasing pierce of all Magic Monkeys in his radius by +2 allows Druids to increase their popping power threefold at 0|0|0. This bonus is also well felt with the Super Monkey, tripling its popping potential as well. He also works as an early Lead popping power if Alchemist is used as a supportive tower instead.
Other heroes can also be used as well despite the bonus, as the inclusion of a non-energy firing Hero can help pop Purple Bloon rushes that can overwhelm Super Monkeys when Druids or Ninjas are not enough. Also, every magic monkey besides the Ninja Monkey has at least one weakness against Purple Bloons.
No magic towers can be placed onto the water, meaning it is harder to complete this mode on tracks with lots of water such as Spice Islands and Peninsula. Alongside, the towers have expensive base tower costs which makes it harder to build multiple defenses on maps with split pathing such as Quad and Muddy Puddles.
As of the 2.0.0 update, Magic Monkeys Only alongside other separate game modes have their own medals that can be collected and displayed on the map's border.
Despite the increased tower/upgrade costs, some players consider the "Magic Monkeys Only" game mode as the easiest of the three "X Monkeys Only" game modes in terms of reaching round 100, while they consider Military Monkeys Only to be harder and Primary Monkeys Only to be the hardest. However, this mode can be extremely hard to complete on some maps, such as Muddy Puddles.