I like the design & colors of Loki but his face just seems less clear than the rest of the sig. Everything else is real crisp & clear and his face just.. isnt. lol.
The second one seems a bit washed out. I would try playing around with the brightness/contrast and maybe even adding a better light source. Theres a strong glow on the top of the head but it doesnt seem to be coming from anywhere.
I definitely like the third one however I dont feel as if the figure blends very well. Looks like they were just placed there randomly and had some stuff throw on top of it.
Overall nice job. Just need a few tweaks here and there