Mostly with Citadel Contrast Paint.
Estimated time: 30 minutes per model.
Base spray model with Chaos Black then Grey Seer 
Guilliman Flesh for skin flesh
Skeleton Horde for horns and hard skin
Magos Purple for tentacles and wounds
Baal Red for clothes and gastanks
Slapchop with Flayed One Flesh 
Leadbelcher for metal weapons
Nuln Oil for metal weapons
Citadel Painting System 9
Base 1
- Leadbelcher
Shade 1
- Nuln Oil
Layer 1
- Flayed One Flesh
Spray 2
- Chaos Black
- Grey Seer
Contrast 4
- Baal Red
- Guilliman Flesh
- Magos Purple
- Skeleton Horde
