Deadly Tranquility

 is an upgrade in the Magic Monkey Knowledge tree. It allows Bloonjitsu to throw 6 shurikens instead of 5, Grandmaster Ninja to throw 9 shurikens instead of 8, and Ascended Shadow to throw 9 shurikens instead of 8. It also adds an extra Flash Bomb and blue mini-shuriken for Ascended Shadow, 6 instead of 5 and 4 instead of 3, respectively, which may or may not be intentional. It requires eight magic knowledge points invested, Diversion Tactics, and a one-time purchase of 500.

Summary
More shurikens per shot increase DPS of the Ninja by a considerable amount. Especially pairs well with Alch buffs, as this one extra shuriken per shot makes more of a difference to overall popping power.

Tips

 * This MK is valuable for players who like to use Ninja Monkeys as their main source of damage. This is especially the case when going for Ninja-only challenges.
 * Do not worry about the adjustment of the angles for shuriken attacks; the extra shuriken helps make the attacks denser and noticeably increase DPS.

Trivia

 * Deadly Tranquility is currently the deepest MK Point that benefits the Ninja Monkey.