From publisher blurb:
Usually, as game masters, we focus more on giving fancy potions to player characters, so I thought it would be cool to make a variant.
Potions and Herbalists: Evil Concoctions brings a new side to potion making: potions dedicated to evil NPCs. It's time for your villains to unleash special effects that will surprise your players.
Imagine a lone, easy-to-defeat goblin who takes a potion and transforms before the party's eyes into a creature far more powerful in the bestiary.
Your villain could gain the ability to curse player characters' weapons and items, decreasing their effectiveness.
Or even gain the ability to observe and control a large area, being able to speak into the minds of the player characters.
The great thing about potions is their chaos factor, after they are imbibed anything can happen, to any type of character, which is also a great way to balance out an encounter.
To gain access to such concoctions, NPCs resort to evil herbalists.
Each evil herbalist has a background page telling their story, a page with instructions on how to roleplay them + a page with extra notes about their items and other curiosities.
Among common effects, we will also have legendary potions. Concoctions long sought-after by evil lords that can sow chaos in a kingdom or bestow powers beyond imagination.
The book provides not only ideas for effects, but also covers lore aspects such as why the potion was created, details about the flask and liquid, and much more.