Venomous Tentacula juice

The Venomous Tentacula Juice it is juice extracted from a Venomous Tentacula plant. It is probably Venomous Tentacula's Sap, and acts like a poison. This "poison" is not deadly but, when consumed creates the sensation of burning on the insides. Also, the skin of the person who consumes it becomes a darker tone, usually purple. Derwent Shimpling probably consumed a big amount of this substance, and his skin colour has become permanently purple. It is hard to distinguish Venomous Tentacula Juice from water, so is very easy to poison someone by simply putting a few drops of the substance in the victims's water.

Behind the Scenes
In Harry Potter:Trading Card Game, the name of this substance is mispelled Venomous Tentacular Juice.