Secret shrink potion converts all affected Bloons into Red Bloons.
~ In-game description
The Bloon Master Alchemist is the fifth upgrade of path 3 for the Alchemist. It allows the Alchemist to throw special insta-shrinking potions every 10.0s. These potions have infinite range and, when thrown, will target the strongest non-BAD bloons, and once splashed onto the main target the insta-shrink potion will subsequently hit up to 200 bloons (or up to 10 M.O.A.Bs, 4 B.F.Bs, 4 D.D.Ts (with camo support), or 2 Z.O.M.Gs), permanently transforming all of the affected bloons into Red Bloons in the process. Each insta-shrink potion has 200 pierce, but MOAB-class bloons consume extra pierce depending on type: MOABs consume 20 pierce, BFBs and DDTs consume 50, and ZOMGs consume 100, while BADs consume zero pierce because they cannot be transformed at all.
Be aware that Bloon Master Alchemist can lose out on a lot of money whenever it transforms strong bloons into measly Red Bloons. It is recommended to only purchase it once income losses are manageable.
However in late game, (Round 101+) Bloons don't give much cash so Bloon Master Alchemist is very useful because you won't be getting much cash anyway without Banana Farms, support Sun Temples or Merchantmen, for example.
Bloon Master Alchemist is still useful in CHIMPS Mode; it can be used to regularly thin out densely packed waves of MOAB-class bloons easily, though obviously the player will start losing money once it starts instantly transforming bloons into Red Bloons. Bloon Master Alchemist is not recommended on shorter maps.
One Bloon Master Alchemist can solo Round 97 on its own, provided that it has enough range to pop the resulting Red Bloons from the transformations.
Additionally, on Logs, it can solo Rounds 94 and 98.