Strategy:Alchemist (BTD6)

This article was last updated for: version 50.2

The Alchemist is a primarily support-focused tower. The top path focuses on buffs, the lower tiers and middle path focus on damage, and the bottom path focuses on income generation.

Base

At base, Alchemist is worse than an unupgraded Bomb Shooter for popping early-game leads such as on rounds 28 and 30, having slower attacks and being more expensive. As a general damage tower it always does 3 damage to bloons it hits thanks to the lasting potion damage. Base Alchemist is very bad for both cleaning up and popping fast bloons, and should only be used with plans to upgrade it later.

Path 1

Alchemist's top path is the most common use for this tower, giving buffs to nearby towers that boost their damage, pierce, attack speed, and range all at once. Berserker Brew especially is one of the strongest support towers in the game for its cost, being used in a wide variety of cases for any of its bonuses.

2-x-x Acidic Mixture Dip (AMD) buffs towers with lead popping power and bonuses to Ceramic damage and MOAB-Class damage. The base buff is applied to a random tower in range of the Alchemist every 10 seconds, and lasts until the target tower attacks 10 times. On average, one attack per second will benefit from the AMD buff, per Alchemist. If multiple Alchemists apply the buff to the same tower, the duration of how many shots will be buffed stacks additively, up to a cap of 50 attacks. When crosspathed, 2-2-0 Alchemist buffs last for 12 attacks, while 2-0-1 Alchemist buffs are applied 1.25x as often. At this tier, neither crosspath is worth its cost compared to just placing an extra 2-0-0 AMD.

AMD is inconsistent if the Alchemist is trying to buff many towers at once, but stronger when stacking a large number of AMD buffs onto one strong tower. The Alchemist buffs one tower if it is the only one in range that can receive it. Bloon Exclusion Zone, which attacks every 0.25 seconds for 4 attacks per second, benefits the most from stacking 5 AMD Alchemists, letting it pop DDTs without needing the more expensive MIB while also boosting the tower's lategame damage. The usefulness of AMD stacking depends on the tower and the defense; Icicle Impale and The Desert Phantom are common targets with their slower attack speed and lack of lead popping, but this isn't recommended since it forces the strongest tower in the defense to be placed away from your other towers. Other upgrades attack too quickly for AMD stacking to be viable. When retrying a round, all AMD Alchemists will buff the tower at the same time, so to get full uptime some should be crosspathed to desynchronize their attacks.

3-x-x Berserker Brew gives a stronger buff with a duration of 25 attacks or 5 seconds, whichever comes first. With +1 damage and +2 pierce, this buff has the strongest value on towers with low base damage, pierce, and a high number of projectiles, such as Bloonjitsu or Overdrive. When choosing a target, the Alchemist will buff the closest target in range which does not already have a Berserker Brew buff or better. If all targets in range already have a brew buff, the Alchemist will wait and immediately throw its brew once a target's buff expires. So, Berserker Brew is still useful with several towers that can accept the buff, as long as it is positioned closest to the tower that is supposed to receive the buff.

For towers that attack less than 3.1 times per second, the buff time is the bottleneck affecting buff uptime, while for towers attacking faster than this, the shot count is the bottleneck. By default, a 3-0-0 brew gets 62.5% buff uptime on slow-attacking towers, while fast-attacking towers have a much lower uptime. Hydra Rocket Pods, for instance, gets 37% uptime with the increased fire rate. Buffing the attack speed of both the buffing Alchemist and the target tower (usually with Jungle Drums) will increase buff uptime if time duration is the bottleneck, and leave uptime the same if the shot count is the bottleneck. With crosspaths, 3-0-1 applies brews 1.25x as often, while 3-2-0 increases the shot limit to 40 and the potion duration to 6 seconds. 3-0-1 has more impact on slow-attacking towers where the bottleneck is buff time, while 3-2-0 is better on fast-attacking towers that exceed shot limit.

The goal is to increase a tower's buff uptime up to exactly 100%. If the Alchemist' attack cooldown is ready, but the intended target is still buffed, the Alchemist will buff another tower, turning a potential 100% uptime down to 50 to 60% uptime instead. This can still be useful if both towers the Alchemist is buffing are equally strong, but is often a downside. Uptime depends on Monkey Knowledge, as it causes Alchemist to apply potions faster. Crosspathing a Berserker Brew is good in CHIMPS or without Monkey Knowledge, but with Monkey Knowledge and Jungle Drums active, an Alchemist with either crosspath will split its brew across two towers.

Unlike AMD, Berserker Brew cannot be applied to the same tower for 5 seconds after the previous potion was given (4 seconds with x-2-x crosspath). This prevents spamming multiple Berserker Brews on one tower to get higher buff uptime on a fast-attacking tower like Sun Avatar. However, despite Sun Avatar's extreme attack rate giving it a very low buff uptime, it still benefits from the buff due to getting double damage and either 1.33x or 1.5x as much pierce for that short time, temporarily tripling DPS for far less than the cost of the Sun Avatar itself. Meanwhile, some towers should not be buffed because it provides less benefits. For instance, Psi barely gets a speed increase at all, as the speed of their attacks in mid-game and late game is determined by how long it takes Bloons to be destroyed, which is unaffected. Also, the damage buffs only affect resonance damage, a small part of Psi's damage output, and the pierce buffs do not let Psi grab additional MOABs in lategame.

4-x-x Stronger Stimulant improves the speed, range, and pierce buffs provided by Berserker Brew. The potion is thrown at the same rate of every 8 seconds, but its duration is increased to lasting 40 shots (55 with 4-2-0) or 12 seconds (13 with 4-2-0). However, this upgrade costs more than another Berserker Brew, and placing a second brew instead also doubles AMD application. Its main use cases are when it targets a tower so expensive the 6% extra speed is worth the extra cost, a tower with very low pierce, or fast-attacking towers where the higher shot limit with 4-2-0 increases the buff uptime for one target tower. Used normally, the longer buff duration lets the Alchemist buff two towers at once, compared to one tower for Berserker Brew, but will not buff a third tower effectively.

5-x-x Permanent Brew will apply the AMD and Stronger Stimulant buffs to all towers in range, with the buffs lasting forever provided the Alchemist is not sold. Due to its high cost, lower tiers are typically preferred during main game and especially in CHIMPS, but Permanent Brew is the only way to get 100% buff uptime on towers with extremely fast attack rates like Sun Avatar, and permanent AMD is strong as well. Crosspaths do not matter here as buff duration is no longer an issue. Other common pairs with Permanent Brew include Destroyers, Full Auto Rifles, and Druid of Wrath + Poplust spam. A Support Chinook can be used to move the Permanent Brew around the map to buff different groups of towers, most useful in Freeplay and Boss Bloon Events.

This upgrade path is actively detrimental against Lych, specifically, as Lych drains these buffs from towers and uses them to heal itself.

Path 2

Alchemist's middle path lets it stand alone as a damage tower, with early upgrades improving damage output while needing cleanup towers to support them, and later upgrades giving them an ability that can deal a lot of damage, but has short duration requiring other towers to cover for the downtime.

x-3-x Unstable Concoction is a cheap source of damage in dense late game rounds that requires other damage towers. As blimps get popped, Unstable Concoction causes explosions that can rapidly open up several more blimps at once, getting massive damage relative to its price, but also releasing large rushes of Super Ceramics at once. This upgrade needs both a tower with strong single target damage and strong cleanup towers like Permaspike or Bloon Solver. 1-3-0 is preferred over 0-3-1 for the extra blimp covered per concoction.

x-4-x Transforming Tonic is a powerful tower for its cost, shining in both mid-game and late-game. At base, its ability uptime is 33%, with 40 seconds between casts that require other defense or stalling to cover for. Pierce is typically the main issue this upgrade runs into, and 1-4-0 does more group damage, but 0-4-1 does do higher single target DPS if that is more important.

x-5-x Total Transformation reduces the ability cooldown and adds the four nearest valid monkeys into the transformation. With random towers, its damage during the ability is less cost efficient than Transforming Tonic, but the extra transformed monkeys can receive tower-specific buffs that Alchemists cannot, like base Ninjas with Shinobis or Druids of Wrath with Poplusts. These tower-specific buffs make x-5-x a powerful late game win condition as long as the player can stall for ability cooldowns. This tier has the same crosspathing tradeoffs as x-4-x, but with its overall higher power level, it has an easier time opting for 0-5-1 for the extra single target damage as its group damage is already great.

Path 3

Alchemist's bottom path is focused around income.

• x-x-3 Lead to Gold is useful for money generation against Dreadbloon, which has custom rounds that greatly increase the abundance of Leads. It also can work well in Apopalypse depending on the round generation, or against rounds with many Lead Bloons like 37 and 38, but otherwise is overshadowed by the next upgrade.
• x-x-4 Rubber to Gold, on maps with one entrance, can generate twice as much extra money as a Monkey Town while stacking with it and other buffs, and being far cheaper. However, the money generation does not seep through blimp layers, requiring an instant kill such as XXXL Trap or Pirate Lord to profit off of them. Use with slowdown towers like Glue Gunners to clump and mark Bloons. The gold potion also removes all Bloon immunities, making it a niche solution to DDTs.
• x-x-5 Bloon Master Alchemist (BMA) struggles heavily against fast Bloons, is useless against BADs, and does not give any cash from converted blimps. Its damage also does not count towards several achievements nor the unlock requirements for Dartling Gunner or similar towers. This upgrade is not worth it.