Dark Alchemy is a Brain Buster exclusive to Dark Ages in Plants vs. Zombies 2. The lawn in this Brain Buster has magic potions placed on some tiles, as they have the ability to grant either speed or toughness bonuses to zombies. The effects will stack up to three times per potion. Zombies hypnotized by Hypno-shroom and Caulipower can also be affected by potions, and as well as Zomboids spawned by Zoybean Pod (Except for the Gargantuar). Plants can not be planted on these tiles. During Dark Alchemy levels, potions will continuously spawn on empty tiles. The only way to destroy potions is by crushing it such as a Gargantuar, a Barrel Roller Zombie's barrel, a Pianist Zombie's piano or an All-Star Zombie's tackle.
In this Brain Buster, it is highly recommended to bring area of effect plants such as Fume-shroom or Snapdragon, as they will help get rid of hoards of boosted zombies. In addition, the Jester Zombie will not be able to deflect anything. If Knight Zombies, Wizard Zombies, or Jester Zombies get a hold of any potion, this can be damaging. Do not forget the Sun-shrooms, as they are very essential and are cheaper than Sunflowers. Instant-kill plants such as Cherry Bomb or Chili Bean are also recommended, as they can eliminate zombies easily if they have consumed too many potions. If the player has them, Hypno-shroom and Caulipower will make great use here, as the hypnotized zombies will benefit from potions too.
Using Shrinking Violet and Enforce-mint are recommended, as they can shrink zombies easily and even a boosted imp will be ellimninated.
Plants vs. Zombies Wiki has a gallery for Dark Alchemy.
When an affected zombie dies, it reverts to its normal size and then starts its normal death animation.
The name of this Brain Buster was revealed in a survey from PopCap Games.
Gargantuar, Barrel Roller Zombie (with its barrel), Pianist Zombie, and All-Star Zombie (only the first potion it meets) can smash potions but it is unknown why the Zombie King cannot smash the potions, despite crushing them.
Dark Alchemy and Bulb Bowling are the only world exclusive Brain Busters to have only two levels, rather than the normal three, with the exception of Beghouled.
If a Zombie boosted by a potion eats a Chili Bean, the Zombie will die and return to its normal form.
This is the first Brain Buster that was used in a Piñata Party, specifically, the Valenbrainz 2016 parties. The second Brain Buster used in a Piñata Party is Beghouled that was featured in a Time Twister Piñata Party.
All zombies that can be affected by potions can stockpile the effects, but will eventually reach a limit after three potions.
The orange speed potions also appeared in Arena as part of some tournaments.
The brains thrown by Cardio Zombies have similar effects to the potions.
If given Plant Food, sometimes Sap-fling can also throw the sap puddles on the evil potions. In this case, the potions will disappear.
The potions in Dark Alchemy were formerly, in the game test files, refered to as "Evil_Shroom seed" meaning that they were programmed as plants and the zombies actually eat them (without animations) when they come across it.
This also explains why certain zombies will crush them. The Zombie King's case, however, is not explained.