Eldar War Walker with Scatter Laser and Starcannon.
Fear it! Or not. Actually, it's only Armor 10, so you would be justified in a more measured reaction. Moderate concern, maybe.
From this angle he looks slightly drunk. Well, maybe Eldar don't get drunk. They're much more epic. Everything they do is laden with drama. We'll say he's teetering upon the precipice of self-annihilation. You know - if his sponsor is asking.
The reality: these things are really hard to position.
The Green is Yellow Olive from the Reaper range, highlighted with Bleached Olive (also Reaper). The rest is Citadel range; Chaos Black, and Desert Yellow over Iyanden Darksun. Highlights to the yellow are Bleached Bone. The gems are Mechrite Red with highlights of Blazing Orange and Skull White. Overall, I'm happy with how it turned out.
Scatter Laser side.
The original idea was to have a Craftworld that used camouflage; a kind of Exodite-Craftworld mix of sensibilities. In the end I decided on a more conservative approach of a segmented color scheme. I think it suits the Eldar architecture better. Camo would have looked too Imperial Guard-y.
Next up: Dire Avengers!