Bloon Trap captures Bloons until full. Select to empty full trap for cash.
~ BTD6 description
Bloon Trap is the 4th upgrade of Path 3 for the Engineer Monkey in BTD6.
It adds the Bloon Trap to the Engineer. Each Bloon Trap can trap up to 500 RBE worth of Bloons instead of 250 RBE in previous games. Additionally, a Bloon Trap will always spawn nearest the Engineer.
Bloons that come over it are trapped inside, though no money is awarded for individual bloon consumption. Like in BTD5, if the trap is collected manually, the player gets twice as much cash as the bloons would normally give; if not collected within 15(?) seconds, or the Bloon Trap is upgraded to XXXL Trap, it will autocollect itself for only the original cash amount as if all bloons were popped normally. MOAB-class bloons and Camo Bloons (unless granted camo detection prior to deploying) will simply pass right through the Bloon Trap. It can hold up to 500 RBE worth of bloons (530 with Bigger Traps). Once full, the Bloon Trap will shake to the left and right and emit an off-white colored aura. Every round, the Engineer will produce a trap and store it in his own "storage of traps" if he doesn't have an active trap already, but any full depletion of his own "storage of traps" will prevent him from deploying any more Bloon Traps.
Try to collect Bloon Traps manually as often as possible, as Bloon Traps do not profit when collected automatically. Additionally, no money is earned when bloons enter, and thus cannot return any money until collected.
There is a 3-second cooldown before the next Bloon Trap can be spawned.
Bloon Traps can be saved in save files. Therefore, they will not disappear when the game has been quitted and re-loaded again.
The appearance of the trap is likely a reference to the Ghostbusters' Ghost Trap.
The upgrade icon shows the engineer either standing on the trap, or violently kicking it.
It makes an eerie electronic humming sound every time it traps a bloon inside.
Before update 12.1, if a Bloon Trap Engineer was affected by Gwendolin's Heat it Up ability, the game would crash.
Similar to BTD Battles, if the Tower is sold in BTD6, the trap will still remain on the ground and keep trapping bloons. But sometimes it will try to find a newly placed Bloon Trap Tower as if the trap is created by the tower. So the new Engineer cannot generate a new trap unless the trap on the ground is filled, and the pops by the trap will be counted to the Engineer.
A Monkey Knowledge Point called "Big Traps" increases the RBE limit to 530, but it erroneously states it can hold 280 RBE.
This has been fixed in the 13.0 update.
As of Version 13.0, the description was changed from "... Tap to..." to "... Select to...", so as to provide a device-neutral description for the Bloon Trap upgrade.
On Version 19.0, all Bloon Trap Engineers always will produce a new trap every time they are upgraded to the Bloon Trap upgrade, rather than only placing a new trap if there are greater than the current numbers of Bloon Traps placed on the map. This does not occur for XXXL Trap. This can be seen here.