All Primary Monkeys in radius get tier 1 upgrades for free.
~ BTD6 description

Primary Mentoring is the fourth upgrade of Path 1 for the Monkey Village in BTD6. It allows all Primary towers within its radius to be granted free tier 1 upgrades. It costs $2125 on Easy, $2,500 on Medium, $2700 on Hard, and $3000 on Impoppable.


  • This upgrade benefit alone is best used with Bomb Shooters, as their Tier-1 upgrades collectively are the most expensive of their kind.
  • Primary Mentoring can be useful as a method of verifying that a Primary Monkey is benefited by Primary Training upgrade bonuses, since only Primary Monkeys are affected by both upgrades.



  • The most expensive upgrade that can purchased for free with Primary Mentoring is the Bigger Bombs upgrade from the Bomb Shooter, saving $400 on Medium each.
  • The most expensive combination of upgrades that become free by the Primary Mentoring benefit is the Bomb Shooter with Bigger Bombs and Faster Reload, totaling a saving of $650 on Medium each.
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