Relentless Glue

"Popped Bloons that were glued leave a blob of glue on the track."

- In-game description

 is the fourth upgrade of Path 3 for the Glue Gunner in Bloons TD 6. It allows bloons to leave a blob of glue on the track upon being popped. Blobs left on the track will last for 5.0 seconds before disappearing, and can glue up to 1 bloon regardless of crosspaths. These track blobs can affect camo, even though the original projectiles do not. These blobs can additionally apply MOAB Glue effects onto MOAB-class bloons, although due to the pierce of each glue blob it is hardly noticeable. The blimp slowdown remains at 37.5% slowdown from the MOAB Glue upgrade, but its glue priority is, in general, one level higher than MOAB Glue, according to the glue prioritization system.

It costs $2,550 on Easy, $3,000 on Medium, $3,240 on Hard, and $3,600 on Impoppable.

Summary
Relentless Glue is another method for the Glue Gunner to counteract its initial lack of proficiency against large groups of bloons, in that it can coat one bloon and transmit to a second target once it is popped. This is crucial, as it allows the Glue Gunner to benefit from the prior upgrade MOAB Glue.

In tandem with its slowing prowess to normal and MOAB-Class Bloons, Relentless Glue allows for the solidification of a good chokepoint where bloons are rapidly destroyed from tower fire, creating more glue blobs on the track to slow those that sneak through. In essence, an effectively used Relentless glue combines the powers of all three paths, being longer and slowing more, soaking through layers, and hitting multiple bloons.

Tips

 * The best crosspath for Relentless Glue depends mostly on what niche must be fulfilled the most. Path 1 is more useful when it comes to improving the crowd control potential of regular bloons, while Path 2 is for optimizing the effectiveness against MOAB-class bloons by maximizing the pierce of the MOAB Glue's blimp slowdown potential.
 * Relentless Glue virtually requires Glue Soak to function as crowd control, as the bloon must be glued as it is popped to leave a glob behind, and because of the slower and more widespread gluing, Corrosive Glue can actually deal some decent damage.
 * A 0-2-4 glue is virtually a waste of this upgrade's unique crowd control potential, as the puddles will almost never be produced, and can only function in extremely niche circumstances, such as combining with high layer towers (which can be considered to be quite rare or expensive) such as Snipers to instantly pop glued bloons.
 * Like all Glues, it works best at the start of the track, however, it is actually beneficial to leave its targeting to First, as it can then glue most bloons behind the first bloon. This is particularly effective in rounds that open with weaker, faster bloons such as pinks or purples.
 * Always combo with Primary Training when possible, as the tower is a lot more effective with even a single extra pierce. It also works surprisingly well in tandem with Alchemist buffs.
 * The tower tends to face competition from Glue Hose and MOAB Glue as both have access to much higher pierce with Glue Splatter. This tower may be useful to allow for camo support or for greater coverage in terms of range, but it is also slower to glue incoming bloons as it relies on the first few bloons to be popped.

Trivia

 * Relentless Glue is likely inspired by the third upgrade of the Glue Gunner's Specialty Building, the Glue Supply Depot.
 * In Bloons TD 6, this is the only way a Glue Gunner can glue Camo Bloons without support and abilities.
 * Relentless Glue, Double Gun (and by extension, Bloon Trap and XXXL Trap), and Robo Monkey are the only towers to be holding a pair of guns.
 * Strangely enough, Relentless Glue neither attacks faster nor attacks two separate projectiles per shot. It also doesn't have bonus popping power either.
 * The description for Relentless Glue was notorious for its poor grammar mistake, as noted by a number of players. Before Version 20.0, the description was "Popped Bloons that were glued, leave a blob of glue on the track." with the erroneous comma.
 * As of Version 22.0, the comma was removed.
 * According to an NK blog post, the original idea for Relentless Glue was that it would leave blobs of glue for every layer of Bloon popped instead. It was deemed too overpowered and lowered the game's performance, and was rebalanced before release.
 * To test Relentless Glue glue track blobs affecting blimps, get a Relentless Glue to stick glue on one bloon, then send a MOAB and let it reach the glue track blob. The MOAB should be slowed down as a result of touching it.