Bloons Monkey City MobileEdit
In Bloons Monkey City Mobile, a Bonus Tower is one free tower to use in a single game. It gives a random free tower to use for the one game. Once a random tower is selected, the Bonus Tower cannot be carried over to other games.
Bloons TD Battles MobileEdit
In Bloons TD Battles Mobile, a Bonus Tower is an extra slot for any random tower, even if the tower isn't fully unlocked yet. It costs 1 to get a Bonus Tower, and it costs 3 to re-roll the Bonus Tower.