All prices are medium mode prices.

The base tower has 3 pierce and shoots once every 1.5 seconds, just like the original Engineer from BTD5.

Base Cost: 500

Top Path:

9-inch Nails: 450 dollars: Shoots giant nails that can pierce through 8 bloons and can pop through frozen bloons.

Quick Reload: 650 dollars: Shoots nails 70 percent faster.

C4 charge: 1000 dollars: Nails explode once when they hit a bloon that is higher than a Pink bloon (once per nail). (The explosion deals two layers of damage and is the size and pierce of the explosion of a Bigger Blasts mortar.)

Nanobots: 4000 dollars: Each explosion sends out a swarm of nanobots that will seek out nearby bloons and pop them. Nanobots do extra damage to MOAB class bloons. (Every bloon hit by C4 charge will spawn one nano-bot that seeks the bloons. The nanobots have 2 pierce and do double damage to MOAB class bloons. Nanobots can pop lead bloons and detect camo, but the main tower cannot.)

Ultimate swarm: 20000 dollars. Greatly increases the number of nanobots spawned and increases their damage to MOAB class bloons. (Each bloon hit by C4 charge now spawns two nanobots that have 3 pierce and do 3 damage to MOAB class bloons.)

Middle Path:

Sentry Gun: 500 dollars: Automatically deploys sentry towers that attack the bloons. (Same as in BTD 5. Sentry spawn rate is affected by top path Alchemists, and each sentry spawned does consume potions from Berserker Brew. Sentries can be targeted by top path Alchemists as well.)

Fast Engineering: 400 dollars: Spawns sentries faster. (Same as BTD5.)

Quick Spawn: 1500 dollars: Every time the Engineer's nails hit their pop limit, they spawn another sentry.

Smart Sentries: 3850 dollars: Sentries become more powerful and each sentry can now be sold for 10 dollars. (Each sentry fires twice as fast and can now pop lead bloons.)

Sentry Unloader: 32000: Activated ability: Spawns a ton of sentries all at once.

Bottom Path:

Energy Blasts: 250 dollars: Once every 15 seconds, creates a small energy blast around the Engineer that strips the regrow property from all bloons in radius and does one damage. (Can deregrow an infinite number of bloons, but the pierce cap of the damage is 50.)

AI: 300 dollars: The Engineer and everything created by it can detect camo.

Powerful energy: 700 dollars. The Engineer's energy blasts will make bloons crackle with energy. Towers that pop a bloon that has the energy crackle will shoot 5% faster for a brief amount of time (The energy crackle does not stack with multiple engineers. Popping another electrified bloon will reset the timer. To receive the buff, the tower must fire the killing shot on the bloon, popping it down to nothing. Electrical crackle soaks through infinite layers, but it no longer affects the bloon after 6 seconds.)

Bloon Magnet: 7000 dollars: Non-MOAB class bloons that are hit by the engineer's nails have to travel to the Engineer, then travel back to the track (they travel at the same speed as their regular speed).

Neodynium-Magnet: 50000 dollars: Bloon magnet works on MOABS, and slightly affects BFBs and DDTs. (BFBs and DDTs only have to travel a third of the distance to the Engineer before returning to the track.)

The Engineer tower's category could be Primary, but I'm slightly inclined to put in in Support since that category of tower is lacking in power.