Vortex, Deadly Master of Air is a boss bloon first introduced in Bloons Monkey City however it was ported into BTD5 Steam/Mobile as the joint first boss bloon. It is an Air environment bloon.
Today the creator will tell you how to deal with him.
Bloons Tower Defense 5 Mobile/Steam Edit
Bloons TD 5 on Mobile/Steam got the new Bosses. Vortex was one of them. He appears every 4 hours (not 100% definite if other Bosses appear) and rewards you with a random item. He looks like a ZOMG bloon from BTD5 on Flash (2011) with a blue/black look and white eyes. He also has more wings.
He is a Boss Bloon. His ability is to release a stun aura and slow down towers' attack speed, for a few seconds. You can counter this as will be shown below. While looking like a ZOMG, he is not as strong (excluding the aura attack, in BTD5 that is.) Unlike BMC or BMCm, where you have Bloon Beacon powers that can bring the boss down to NOTHING, in BTD5 you get more of a challenge. He will never appear in natural BTD5 freeplay. He only appears in designated Boss spawn times.
Since he can stun ALL towers within radius, spamming SPACED towers will help. 0/3 or 2/3 Dart monkeys stand a chance against him. If you can afford it, you can do as much damage as possible at one point, then buy a quick x/4 Bomb Tower and activate the MOAB Assassin ability to kill him instantly if you get his HP down enough. Another strategy is to get towers that can kill Bosses with ease. Try the Spike Factory if you are curious. He has 2000 health in BTD5. FUN FACT: An early exploit was Hypersonic Tack Shooters which could kill him with ease. It is unknown if it works or not.