Valenth

Most leupaks (those created from venom transformations are the exception) possess a crystalline third-eye structure upon their foreheads.

This is the facet; a small piece of the Mirajin crystal which true leupaks are born from, similar in structure to the crystals formed on boralion dragons.
Facets contain a leupak's vital essence-- in other words, the concept, thought or idea which they sprung to life from. Touching the facet of a living leupak with bare skin will flash such imagery through one's mind.

Each individual leupak's facet may be different; while basic shapes are common, many reflect the theme its leupak is based upon.

Facets buzz softly with energy, and make powerful foci in magical and alchemical endeavors, especially those involving dreams, chaotic magic, or a subject linked to the facet of the leupak in question.
For this reason, facet-crystal is a rare, highly-prized component in all manner of magical work. A facet cannot be removed from a leupak without killing it, however; the external portion of a facet is only the tip. The structure extends through a leupak's skull, rooting into its brain.

Leupak hunters often poach the creatures for their facets, severing the head and leaving the rest behind. Such black market goods fetch high prices in Soril, especially the facets of powerful leupaks, which usually have more energy and yield greater effect in spells and devices.