Board Thread:Questions and Answers/@comment-67.85.255.241-20130703022847/@comment-2189621-20140210222641

It's also another water tower (About freaking time), and has an insane cost/power ratio. You're spending 350 for something that shoots homing darts at the speed of a Ninja monkey, the third fastest tower in the game.

Very hard to unlock, though. You need to pop 2 MILLION Bloons to get it. Very worth it, though.