Summon Whirlwind

Summon Whirlwind is an upgrade for the Monkey Apprentice. A Monkey Apprentice with this upgrade is called a Disciple of Air. It allows the monkey to summon a whirlwind that can blow Bloons closer to the start.

Strategies
-Put Monkey Apprentices near the end of a track so that they're more efficient in saving you lives (putting them in the beginning won't blow them back much).