My take on House Drakkus colour scheme (from the Freeblade mobile game). Going for a much lighter, greener turquoise.

1. Primed with Grey Seer for armour (anything not to be silver) and Leadbelcher for everything else (the mechanical parts)

Mechanical working parts

1. Washed with Nuln Oil
2. Drybrushed with Necron Compound
3. Inner piston rods painted over with brighter silver Ironbreaker

Turquoise

1. 3:1 ratio of Sybarite Green to Kabalite Green , heavily thinned down
2. Recess shade of Coelia Greenshade (usually multiple layers)
3. Edge highlights on sharp edges with Temple Guard Blue and rivet heads

Gold (trim & Inquisition skulls)

1. Basecoat of Retributor Armour
2. At least 2 thin layers of Auric Armour Gold
3. Recess shade of Reikland Fleshshade
4. Edge highlighted with Liberator Gold and also rivet heads

Inquisition symbols

1. Basecoat of Khorne Red
2. Recess shade of Carroburg Crimson
3. Edge highlighted with Wazdakka Red , corners dotted with Wild Rider Red

Bone (skulls)

1. Basecoat of Zandri Dust
2. Layered with Karak Stone
3. Recess shade of Nuln Oil
4. Highlights of Screaming Skull

Scrolls/Parchment

1. Basecoat of Rakarth Flesh
2. Layered with Pallid Wych Flesh
3. Recess shade of Agrax Earthshade (only 1 pass!)
4. Edge highlight of White Scar
5. Text written with Dryad Bark

Brass (exhausts, thermal cannon tanks)

1. Basecoat of Warplock Bronze
2. Layered with Brass Scorpion
3. Washed with Agrax Earthshade
4. Edge highlighted with Runelord Brass
5. Exhaust carbon: stippled Abaddon Black with drybrush
6. Muzzle burn: Multiple layers of (front to back): Nuln Oil , Drakenhof Nightshade , Druchii Violet , Seraphim Sepia

Miscellanous

1. Cabling: Abaddon Black with subtle highlights of Eshin Grey
2. Wings on chest: based Celestra Grey , recess shaded Drakenhof Nightshade , layered Ulthuan Grey , highlighted White Scar
3. Freehands on pauldrons: Celestra Grey to Ulthuan Grey , Mephiston Red , Abaddon Black , and White Scar
4. Lenses: Spiritstone Red on Stormhost Silver or Leadbelcher (window was Soulstone Blue instead)

Water Transfers/Decals (curved surfaces of pauldrons)

1. Soak transfer backing with Micro Set
2. Apply a layer of Micro Set to the surface decal is being applied to
3. Move decal to surface, dab excess liquid with paper towel
4. When completely dry, apply Micro Sol, brushing from the middle out to remove any air bubbles
5. Remove excess liquid with a damp brush to avoid staining
6. Apply Lahmian Medium to entire surface to remove glossy finish

Base

1. Astrogranite applied
2. Wash of Agrax Earthshade
3. Drybrushed with Tyrant Skull
4. Rim painted with Abaddon Black

Surface Finish

1. Glossy finish of 3:1 mix of Glossy Varnish : Ultra Matte Varnish on metallics and lenses
2. Matte finish of ~50/50 mix of Ultra Matte Varnish : Contrast Medium on everything else