Ties the model into the basing scheme that uses Martian Ironearth for the bases. I used the Vallejo rust pigments to get a closeish match

Picked him up at Warhammer World last summer along with the metal Azreal before they replaced him

Ezekiel of the Dark Angels is still metal

They are just Geek Gaming Scenics pre-made grimdark rubble: https://www.geekgamingscenics.com/collections/base-ready/products/lukes-aps-base-ready-grimdark-city-rubble