With all the radiation around after the bombs fell, even usually docile-ish creatures grew into nightmare horrors, including deer. They’re now found in Radstag Herds that you can also get for your Fallout: Wasteland Warfare collections now.
From the website:
This set is part of the FORGED IN THE FIRE wave for Fallout: Wasteland Warfare!
The Radstags were once ordinary deer, living their lives in what would become the Commonwealth. The Great War mutated and twisted these animals, giving them second heads, small additional legs, and pus-filled radiation cysts. They are relatively docile animals but can be vicious when threatened.
Look out for other miniature sets in the Forged in the Fire wave!