Blade Maelstrom Ability: Covers the area in an unstoppable storm of blades.
~ Bloons TD 5 Description
Blade Maelstrom is the final upgrade on the second path of the Tack Shooter in BTD5. It is unlocked upon reaching Rank 20. It is the special ability for the Tack Shooter in BTD5, BTD Battles and BMC. When activated, the Blade Maelstrom rapidly shoots two streams of blades, which spiral outwards. It costs $2295 on Easy, $2700 on Medium and $2915, Hard and $3240 on Impoppable. Its ability cooldown only lasts for 20 seconds.
In BTD6, this upgrade returns as the fourth upgrade of Path 2 for the Tack Shooter. It also creates two rapidly shooting streams of infinite-pierce blades that spiral outwards clockwise for 3 seconds. However, there is now an initial cooldown of around 5 seconds before activating a recently upgraded Blade Maelstrom. Cooldown is 20 seconds, like BTD5.
Each of the blades have unlimited pierce, making it good for thick groups of bloons (Helpful if Regen Farming gets out of control and it's cheaper than Ground Zero). However, you may need 2 or 3 to destroy all Regenerating Bloons. Several of them can destroy a whole map of regenerating Ceramic Bloons.
Blade Maelstrom will deal more damage to bloons closer to its proximity, due to the higher density of blades.
It's possible to destroy a few MOABs at Monkey Lane if players put 8 Blade Maelstroms in the center of Monkey Lane. This works with x/4 Tack Shooters. Tacks must be 2x4 to do this. Activate the Blade Maelstrom Ability when the MOABs are in the right of the 2x4 Tack Space.
Despite the description stating it is "unstoppable," Blade Maelstrom will be stopped by Lead Bloons. This can be prevented by a Monkey Intelligence Bureau (x/3 Village in BTD5, x/3/x Village in BTD6) or other lead-popping grant (only possible in BTD6).
It is possible to take down the outer layer of a MOAB with this ability if players time it correctly. 10 Maelstroms can take down the outer layer of BFB.
There is a bug where the ability will never hit Camo Bloons, even if the tower is next to a tower permitting Camo detection. This doesn't happen in BTD5 Mobile/Steam or BTD6.
The Blade Maelstrom has the fastest cooldown in BTD5, taking only 8 seconds to recharge in fast forward mode.
Blade Maelstrom is the cheapest Activated Ability in BTD5, costing $4140 (in total as a 0/4) in Medium. The second cheapest is the Absolute Zero from the Ice Tower, costing $4800 (in total also as a 0/4).