An Advanced Creature Profile by Vincent Groth.      

The Krog stands nine feet tall. Krog are a cross breed of Truglin and a Troll, can reproduce, and can function outside of the Horde. They have stony skin, large hulking bodies that can blend into rocky surfaces when stationary. They have thick moss like fur, and small beady eyes. Krog have metamorphic skin which as they grow up takes on the characteristics of the most common stone in their area.  

Krog are strong, have blood that calcifies when meeting oxygen. They have a slow regeneration. Krog are not affected by the Horde mind at all. 

The Krog are ambush predators, feral, and primarily survive by preying on other Greenskins. Krog are allowed to live in the mountains to ward off Dwarf and Human patrols and advances. 

The Krog are not bound to the Horde Mind and do not have its benefits or downsides. They are feral, bestial, vicious, and dimwitted.