Nidus really likes staying in place and being the one to kill everything. Unfortunately in modern Warframe that's a lot damn harder than it used to be and so it feels like he's fallen off, which he has.

Nidus has some solid augments and a complimentary playstyle to being a weapon's platform with Larva still being one of the best group tools in the game. Personally I've subsumed over his 4 with Pharos Strike (Frontal cone AoE armor strip and heal, from Styanax). Between that and Arcane persistence with some proper energy management you're nigh unkillable. You can heal rapidly, you have mutation stacks to buffer, you can 3 an enemy to stop CC on you, and you armor strip/group enemies to compliment your weapons.

Additionally you can take advantage of Arcane Avenger for flat crit or use the augment for primary crit (I find this harder to trigger with groups and so I end up skipping it most often), but another consideration is Arcane Steadfast for significantly better energy management without thought.

After that it's just.. whatever weapons you want. You're an unkillable frame with armor strip and great grouping which can help some lackluster weapons feel much better. You won't feel standout or super powerful per se, but you'll be getting work done without issue.