Greevil

This courier's appearance is determined by the types of Essences it was exposed to while still a Greevil Egg. Players could use their Greevils in Frostivus 2012's The Greeviling game mode, where each Greevil was given a set of abilities.

Properties
Each Greevil courier has a set of possible cosmetic properties that differ depending on the Essences that were used on its egg.

Effects
Up to three Unusual Essences could be socketed into a single Greevil Egg, and each increased the intensity of the particle effect corresponding with the color of the hatched Greevil courier: the first imbued Unusual Essence resulted in a general aura effect, the second added a searing eye effect, and the third added a particle trail.

https://www.youtube.com/watch?v=nhttgI6A3m0

Gallery
Greevil Грявол