Based mostly on video linked in description

1. Base spray with Chaos Black

Base layers

1. Entire horse barding with Flesh Tearers Red
2. Cover large (non edges) surfaces of barding with Abaddon Black
3. Gore-grunta Fur for the all the skin of the horse, might need to apply twice
4. Cover all the armour and shield of the knight with Mephiston Red
5. Use Rhinox Hide for the leather straps and saddle parts, as well as little straps holding up the armour and such
6. Use Retributor Armour on the gold accents (see box art), as a base layer
7. For the bone and hooves of the horse, use a white like Corax White or Wraithbone
8. Add a layer of Iron Warriors on the chainmail of the horse, and Leadbelcher on the main weapon and the various studs and rings on the mini.

Shading / Contrast

1. Cover all the white bone with Skeleton Horde
2. Add a layer of Agrax Earthshade on all the Retributor Armour gold parts.
3. And for all the leather and horse skin, as well as al the Leadbelcher metals, cover with Nuln Oil
4. For the chainmail done with Iron Warriors , add a layer of Skeleton Horde
5. Cover all the knight's armour with Carroburg Crimson

Horse Barding

1. Roughly highlight the horse barding with Khorne Red on all the edges
2. Cover the sharpest edges and lines with Gryph-hound Orange
3. Dot the sharpest tips and ridges with a tiny bit of Bestigor Flesh or a white such as White Scar

Knight

1. Go back to Mephiston Red to bring back the colour on the bigger plates / areas. Leave the shade in the corners and shadows.
2. Highlight with Evil Sunz Scarlet on even smaller areas and edges.
3. Minor edge higlight with Wild Rider Red

Other

1. Go back to the gold ( Retributor Armour ) and once again bring back the colour on the bigger areas while avoiding the recesses.
2. Highlight the gold with Liberator Gold . Mix with a white and do another tiny edge highlight for maximum effect.
3. In the same way as the gold, bring back the colour on the leather parts with Rhinox Hide .
4. Highlight both with Bugman's Glow or Gorthor Brown
5. Mix Abaddon Black with Sybarite Green : and cover the lighter areas of the cape from the horse, the cape from the knight, the reigns, tail and horsemane.
6. Add some more Sybarite Green to the mix and focus on the lighter parts again.
7. Repeat previous step twice more, going more subtle each time.
8. Add a pure edge highlight with undiluted Sybarite Green :
9. Apply Iron Warriors : to bring back the metallic colour on the various metal parts.
10. Highlight these metals with Stormhost Silver and highlight the chainmail with Liberator Gold
11. Reapply the chosen base colour of the bone as a highlight.