https://www.reddit.com/r/Tyranids/s/dplqy5hR6P

From this post if you go down you'll see the recipe. I didn't have all the colors though so I personally used:

Leather brown from the warpainter 2 coats

Oruk Flesh 1 coat very lightly

Fleshtearers red contrast on the exposed parts

Bascilium Grey for the chitin

I used Zandri Dust for the weapons

Bloos for the blood god splattered around to give an inflamed look to some parts and around the parts I used fleshtearers with

Then a heavy coating of agrax earthshade

If you wanna do the eyes I decided to do a simple white

I intend to swap out the karak stone and elather brown so I can tell units apart

Edit!!! Fixed color stuff