If you only plan on playing Nidus in a premade group OR only plan on playing him with a Wisp specter, OR plan on using Vazarin, subsume off his 4 instead of his 2. I'd also recommend having an armor strip build and a roar build available to be able to switch between them freely based on what the group already has or needs. If you have trouble sustaining the gloom build just take umbral fiber or intensify off for flow.
Also, yes, I'm aware that ranking Nidus under the assumption that you're in a premade group isn't entirely consistent with the rest of the tier list (though I always do consider their group potential for viability) however, I feel Nidus is a special case as his entire gimmick is group utility.
Archon shards would definitely be 5x armor, unless REALLY trying to speedrun steel path exterminates or get funny Wisp numbers.
I messed up my polarities when forma'ing ):
0:00 Intro
0:25 Builds
4:03 Weapon Loadouts
5:33 Focus Cchools and Companion
7:03 Regulations (Important)
8:00 Topic One: KPM
8:35 Topic Two: Survivability
9:50 Topic Three: Viability
13:51 Topic Four: Is he fun?
15:14 Conclusion
Frame that gets outshined by his own specter, feels bad. Still good though.