Here's how it works:
* It does not change the pet's base colour. You can use it on a pet of any colour, and it will only affect the eye colour.
* It has a random effect. The potion will give your pet a random eye colour from the list of available colours for their species.
* It can be purchased from the Neopets shop. You can find it in the "Other Items" section.
* It is a one-time use item. Once you use it, it's gone.
So, if you're looking for a way to give your Neopet some unique and colourful eyes, the Dark Vine Potion is a good option! Just be aware that you won't be able to control which colour your pet gets, so you'll have to be prepared for a surprise!