WIP: Necron Doom Scythe #3

Randomizing the size and placement of the lichen clumps is spot on – I would clump smaller bits right next to larger bits too, to get a more realistic vegetation pattern. Like there's a large plant in a fertile spot, with smaller offshoots of that plant spreading out from it. I think lichen looks best growing out from/clustered up right next to rocks, too. That's where moisture would accumulate and there would be protection from those harsh alien winds. You could even put them all on one side of the rocks (like the "east" side), I believe that's how lichen grows – all on one side of rocks, away from prevailing winds.

For coloring the lichen, I would recommend red and orange washes applied sparingly to the lichen, in a mottled fashion. I like the contrast of the cream color next to the red ground, you want to keep that brighter color, but you could dab on some patches of red and orange to tie things together. You could also consider dabbing on some glue to the lichen and sprinkling red/orange flock on the lichen, to simulate buds or flowers on the plant. That would make them more complex and realistic.

Reiterating the above really, the lichen would probably look better more clumped up, to prevent the "even spread" look you've inadvertently created. Also, you might consider adding splashes of colour to the tips of the bigger lichen clumps, simulating alien flowers/buds and to break up the red-on-red a little; some vibrant green/pink for example.

The main issue I see with the base isn't really the colour of the lichen but how it is applied. What I mean is the base is a handful of evenly placed rocks and then a handful of same sized, evenly placed lichen. I think the base would look way better if some of the rocks were different sizes, grouped up together and more in an irregular pattern with the lichen in more logical, more random looking places (also different sized ones would help quite a bit).

The only other thing I just noticed as it wasn't apparent before just due to how the models were painted (primarily metal with red accents) is that you have a red model on a red base (similar colours of red too) and they kind of get lost. This is a minor thing though as I am sure once you see the army in force it will look great.