Mmm, yeah. Nidus as an infested based Warframe would be pretty hard to do well. I do like the look of the body model, and I love the forearm and calf design, though I wish there was slightly more color variation on those particular parts, as if there were bony lumps or darker cancerous tissue, but only slightly more. The helmet however, though the color pattern is really cool, is simply too close to the original in my opinion. Maybe if you tweaked the shape on the mutation masses coming off his head and maybe add in a couple smaller ones at the jawline or cheeks. I'm trying to give ideas to make the helmet more unique but I don't know if it's helping much. Just don't be affraid to stray far from the original. On the torso, for the v2 mutation, maybe hint at some more glowing mass down near the abdomen instead of confining it to the chest and shoulders. Also, it seems a little too bright in some of your pics, maybe lessen it just a little and add a little more irregularity to the brightness within. Not so dark as v1, mind you.

Anyway, if you read all that, thx for reading! I hope it helps, and I do so dearly hope this one makes it in eventually. Good luck!