The Alchemeister is the Mini-Boss of the Explodatorium. Initially appearing as an old man, once he consumes a potion he transforms into a large beast. He possesses 23 hit points; more than even full bosses and if the player collides with him the player will lose one full health bubble. If he is defeated in regular form he will just drop gold, but however if he is defeated in his beast form he will also drop a turkey.
In the credits of Shovel of Hope he can be seen in Plague Knight's potion class in which Plague Knight seems to transform him into a woman resembling the Magicist. After Plague Knight joined the Order of No Quarter in Specter of Torment he could be seen attending Creech's bar.
- In his normal form, he throws variously colored vials that explode when they hit the ground and damage the player if they hit him.
- In Specter of Torment, since the ground is covered with water flow, some of the vials may cause continuous explosion.
- In his beast form, he runs back and forth across the screen, increasing speed as he takes damage.