A cragadile.
Cragadiles are extremely rare Tundra predators. They resemble massive crocodiles comprised of hardened stone. They are extremely resilient and immune to all forms of poison and disease. They can only be destroyed via heavy munitions or a well-placed shot through one of their eyes.
These creatures are seemingly not affected by the Hoarfrost. This makes them easily distinguishable in the Tundra's ocean of snow, as they are still green in color.