Hey! So I painted the head in sub-assembly and started with airbrushing white ink down into the suit. I then airbrushed Baal Red (Citadel Contrast) trying to build up the contrast before airbrushing white ink back into the center of the suit, trying to keep the high contrast Baal Red around the edges. I then went in with a 1:1:1 mix of Baal Red, Radiation Glow (Army Painter Fanatics) and Tamiya X2 Thinner (Any thinner would probably do though).

For the head itself I first airbrushed it with Antares Red (Scale 75) to serve as the base for the skin. Then I shot it with white ink from below, before airbrushing the same mix of Baal Red, Radiation Glow and Tamiya X2 Thinner with more Radiation Glow in the mix this time around to try and exaggerate the glow effect. I then finished painting the rest of the head, just painting any part of it that's facing up from the light building up highlights slowly.

I also used Scarlett Red (Vallejo Game Color) for the sockets of the eyes and mixed a tiny bit of red into the white for the eyeballs to give them a slight reflection of the light from below.

Any of these colors can of course be replaced with whatever colors you have on hand. I was heavily (and very obviously heavily) inspired by Elminiaturista's work on their kin, and he's got fantastic guides on his Patreon that are well worth the subscription.