There are several plants, herbs and other natural materials that are extremely toxic to Vampires. Vampires can also find themselves in a uniquely deadly situation by ignoring a simple human custom. Garlic: Upon consuming garlic a Vampire will immediately revert to its natural form complete with black eyeballs and visible fangs. While under the influence of garlic a Vampire will be unable to assume a convincing human like form and must appear as what they are.