The Ultimate Succ. This build focuses on grouping enemies up and priming them full of status effects with a Helstrum.
Check out the Helstrum Primer build here: https://overframe.gg/build/547340/
If you do not need priming, I have an alternative build that instead grants you with a critical damage boost to all weapons in addition to grouping: https://overframe.gg/build/602313/nautilus/super-grouper-grouping-crit-boost-nautilus/
MODDING NOTES
Cordon and Manifold Bond - [Cordon] allows your [Nautilus] to group enemies within 30 meters into tight clusters. Manifold will reduce the cooldown of [Cordon] whenever you kill enemies with 3+ status effects on them allowing your Nautilus to spam Cordon and constantly group enemies.
Calculated Redirection and Accelerated Deflection - Survivability mods for your [Nautilus]. [Redirection] gives more shields which gives a higher shield gate timer, and Deflection makes the shields recharge faster.
Primed Regen and Momentous Bond - These mods help revive Nautilus faster when it is disabled. Kill a few Eximus units and it'll be back in no time.
Assault Mode and Duplex Bond - Assault will make your sentinel attack anything within 30 meters of you. Duplex will make 3 clones of you sentinel. Clones do not use [Cordon] or any other precept abilities, however they do attack with the equipped weapon so they'll basically prime even more enemies for you.
Synth Deconstruct - This is only needed if you're running [Equilibrium] on your Warframe as it provides a greater chance for health orb drops. If you aren't using Equilibrium, you can replace Synth Deconstruct with Animal Instinct, Aerial Bond, or Guardian.
Vacuum - Mandatory loot magnet mod.