Two version of this one : one with helmet, one bare head.
He don't look like a smart guy, but, hey, what do you expect from someone choosing to follow the black lord of necrosis :O
Some ref for helmet, ork face, colors...
A lot of inspirations from Johan Grenier, Paul Bonner and Karl Kopinski !
Comment and critics welcome ! :D

Ref :
https://www.artstation.com/artwork/JV1ed
https://www.artstation.com/artwork/kdbd0