Strategy:Engineer Monkey (BTD6)

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Engineers have relatively low upgrade costs with a large variety of uses ranging from DPS to support and even income generation. Notably, they make more usage of crosspaths than any other tower, with each crosspath bringing numerous different effects for each upgrade. Good choices with crosspaths, therefore, are core to Engineer strategies.

Base

The base tower is similar to a base Dart Monkey, but with a slightly bigger footprint and slightly higher range, pierce, and attack rate. This makes it a good group popper. On the other hand, it costs nearly twice as much as a base Dart Monkey. Still, it is a viable starting tower and is commonly used in conjunction with a base Dart Monkey to start CHIMPS.

Path 1

Path 1 focuses on DPS through usage of its Sentry turrets. This can be rather inconsistent, as Sentry placement partially relies on RNG, but is still useful and can even be used for group popping, as each Sentry can have its individual target priority set differently.

Sentry is one of the tower’s core upgrades, allowing it to deploy multiple sub-towers that shoot the same attacks as a base Dart Monkey, with the same range as the Engineer. This has many advantages, as it allows the Engineer to attack outside of its range and pop many bloons at once, depending upon placement. With Vigilant Sentries, even more Sentries can be active at once. One of the biggest advantages of Sentries is that they inherit all buffs that the Engineer who deployed them received, allowing for the buffs’ effects to be multiplied over and over again with each Sentry. Attack speed buffs to the Engineer also cause Sentries to be deployed more often.

Faster Engineering allows deployment of Sentries, Cleansing Foam, and Bloon Traps at twice the speed as before. This allows for even more Sentries to be active at once, and used-up foam and traps can be quickly replaced. Sprockets doubles the attack rate of both the Engineer and its Sentries, and if crosspathed with Pin, allows Sentries to stun bloons just like the Engineer.

Sentry Expert allows the Engineer to create different kinds of Sentries depending upon what bloons are onscreen and which ones of those the Engineer determines to be the biggest threat. Other than placement of the Sentries, the main struggles this upgrade has is the tower’s inability to see camo. Laser Sentries are deployed against DDTs despite the lack of Camo detection, making it difficult if there are many purple bloons in the same round. However, the upgrade shouldn’t be counted out, as the specialized Sentries won’t struggle in rounds with a consistent bloon type.

Sentry Champion switches out all Sentries for larger ones that have a greater range and rapidly shoot plasma balls with decent popping power, releasing a large, high-damage explosion when expiring after a short delay. While it excels at single-target DPS, the upgrade overall isn’t a great DPS option compared to others. Fortunately, external speed buffs can easily eliminate its weaknesses. Its relatively low cost allows money to be spent on those buffs. The Sentries’ inability to damage purple bloons is another weakness, requiring external support to handle rounds with many of these.

Path 2 crosspaths are generally better for building up the first path, due to the extra range and damage against blimps and fortified bloons. For mid-game, however, or for other Engineers after Sentry Champion is built, Path 3 is also viable, as it grants far higher pierce to the Sentries, and stalling properties once Sprockets is purchased, as well.

Path 2

Path 2 focuses on support.

Larger Service Area grants both the Engineer and Sentries (if purchased) a larger attack range, also allowing Sentries and Bloon Traps to be deployed in the increased range. Additionally, it allows the player to choose a spot where the Bloon Trap is deployed, instead of the Engineer simply placing it close by. This allows better management of the tower’s assets and lets it cover a massive amount of the track when crosspathed with Sentries.

Deconstruction allows the Engineer and Sentries to do extra damage to Fortified and MOAB-class bloons, and it causes Bloon Trap and above to automatically strip fortification when trapping bloons. This upgrade is perfect for crosspathing with Sentries and reducing their higher tiers’ more glaring weaknesses. Additionally, with Deconstruction, early MOABs will be eliminated in no time if several Sentries and the Engineer are all firing at them at once.

Cleansing Foam allows the tower to spray foam that can decamo and de-regrow bloons, while also removing the lead layer of lead bloons. It also quadruples attack and deployment speed for 1 second at the start of every round. While the foam cannot actually damage bloons with lead properties, namely DDTs and Dreadbloon, it does bypass the extra health Fortified Leads have. However, powerful anti-lead measures can usually be secured well before Fortified Leads appear, so it is mostly useless for this purpose. When crosspathed with Sentries, the Sentries’ nail attacks remove lead and regrow from (normal) bloons, and can decamo them if they have camo detection. Cleansing Foam can be used on rounds with many DDTs, especially when paired with Thicker Foams, allowing powerful towers that can’t see camo, such as high-tier Boomerang Monkeys, to quickly eliminate the DDTs.

Overclock is one of the best upgrades for the tower, as it allows the Engineer to give a tower of the player’s choice a massive attack speed buff. Banana Farms, when Overclocked, make much more money, while Villages just get increased range (except for Primary Expertise, to which both the attack speed buff and increased radius is applied). The upgrade also gives a hefty increase to the Engineer’s pierce, while granting more pierce to the Cleansing Foam as well. Overclock rewards strategies that rely on powerful towers rather than many towers, and its uptime for below Tier 5 towers is equal to or even greater than its cooldown, allowing said monkeys to constantly have a very high attack rate. This can turn towers that are middling at DPS, such as Sentry Champion and Apache Prime, into masters of DPS.

Ultraboost provides an even better buff: it lasts a full minute regardless of tier, has a shortened cooldown, and gives a small, permanent attack speed buff to the tower it is used on. This permanent buff stacks up to ten times on the same tower, totaling a permanent buff almost equal to that of the Overclock ability buff. On top of that, the permanent buff stacks with the Overclock/Ultraboost ability. It also gets a big pierce increase to both the nail and foam attacks. Focus should be switched from towers that can keep the uptime to the most powerful, since the uptime can easily be kept to permanent. Towers with an already huge attack speed, such as Avatar of Wrath and Flying Fortress can have their attack speed multiplied many times over to wipe out even Fortified BADs and Bosses with ease. It is best not to use it against Lych, as it will simply allow him to heal large amounts of health while stealing the boost.

Crosspaths become less and less useful as you level up, and overall, Path 3 is the better option, as while none of the crosspaths benefit the Overclock or Ultraboost, the extra pierce and slowdown effect given to the Cleansing Foam allows it to be used as a viable decamo tower, particularly against DDTs.

Path 3

Path 3 focuses on taking out Bloon rushes.

Oversize Nails increase the pierce of all weapons, also allowing the Engineer and Sentries to pop frozen bloons. This allows a 1-0-1 Engineer to be a cheap option for very quickly detonating bloons frozen by Ice Shards, making the section of track that the Ice Shards is covering very hazardous.

Pin allows the Engineer (and Sentries, if Sprockets is purchased) to stun below-ceramic bloons while still leaving them poppable to monkeys that can’t pop frozen bloons. It also makes Cleansing Foam, if purchased, temporarily slow down all non-blimps that pass through it to half-speed, allowing for more time for towers to eliminate rushes. Pin is counted as a stun, so towers that do more damage to stunned bloons, such as Flash Bomb Ninjas and Sauda, can be paired with Pin Engineers to further increase their potential.

Double Gun doubles the Engineer’s attack speed, and makes Sentries shoot two nails per shot instead of one, doubling their damage. This can carry the early game provided it has anti-lead and -camo support, and can more reliably bring bloon rushes to a halt.

Bloon Trap makes the Engineer create an on-track trap that can instakill up to 5 ceramics, or 6 with Big Traps, and collect double the money after it is full compared to what you would get for popping them normally. The value of this is heavily boosted when near Monkey Town/City Villages or when trapping bloons affected by a Rubber to Gold Alchemist. Banana Farmers can autocollect full traps, so if one is on screen, you can place the Engineer nearby if you don’t want to micromanage it. Otherwise, place it near the beginning of the track so that other monkeys don’t steal bloons that would otherwise feed income.

XXXL Traps fulfill even more uses, instakilling up to a ZOMG (DDTs can only be trapped if visible), immensely increasing the number of bloons the trap can hold, and giving triple the amount of cash compared to regularly popping it. While using it to get rid of slow-moving blimps is the most common use, it can also be used mid-to-late track to tank thick rushes that get through, having an almost comparable reliability of doing this to Perma-Spike.

Crosspathing generally depends on preference: Path 1 allows for quicker deployment of traps, but the Sentries may undermine the traps’ income generation by stealing pops. Path 2 is usually preferred thanks to the custom positioning of traps and ability to handle fortified rushes, but suffers against constant rushes due to being unable to replace the traps quickly enough.