Shinobi Tactics is the third upgrade of Path 2 for the Ninja Monkey in BTD6. It allows all Ninjas around its radius to increase attack speed by 8% (multiplicative). This upgrade can stack, stacking to up to 20 times or increase attack speed up to 430% more than normal. It costs $765 on Easy, $900 on Medium, $970 on Hard and $1,080 on Impoppable.
Tips
Usually, it is best to leave Shinobi Tactics as 0-3-0, unless it is to increase Shinobi Tactics coverage range, in which 1-3-0 should be enough range to reach nearby high-level Ninjas for that significant attack speed boost.
Trivia
Shinobi Tactics is one of the few upgrades that can boost nearby towers of the same type, the other being Poplust and Elite Sniper.