Prior to Duviri, I put in some time acid testing boilerplate builds to get all my frames to scale into SP Circuit. I'll summarise the work here. I'm happy to answer any questions in the comments. Hopefully this will be of some use!
As a bonus, none of these require energy->shield mods or Decaying key, although using either or both adds an extra layer of survivability.
Infinite Scaling
Condemn helminth! Easily the comfiest and most reliable way of shield gating, as it CCs enemies and shield gates most frames in just two or three targets affected. The ability has a "soft" slam animation that has reduced priority over double jump and parkour, so casting during a double jump or bullet jump will keep you airborne. It's also a one-handed cast so does not interrupt reloads, and you can shoot mid-cast.
The important requirement is that you need to compensate range or strength on Overextended or Narrow Minded builds, or use the next helminth option.
Pillage helminth. Unlike Condemn, provides absolutely no CC, so I only recommend this on frames that have some kind of innate CC such as a slow, distraction, confusion, etc. Also a full-body cast so it prevents movement and other actions, and comes in at twice the casting cost.
Infested
The heck faction... until now. Silence helminth completely reduces them to melee, which should not be a problem with Warframe movement. Just don't get in a slap fight with any Disruptors or Toxic Ancients (or Venomous Eximus).
Silence prevents grapple hooks and Osprey clouds, as well as all Eximus casts. The only remaining mechanics are the Ancient stretch arm attack and MOA goop and clouds, but the MOA attacks do fixed low damage, so no biggy.
I just want to face tank to level 300
Health Conversion from Simaris, Arcane Blessing from Conjunction Survival, and your choice of Fractured Blast (same build constraints as Condemn) from Citrine, or Lycath's Hunt from Voruna (preferably don't dump stat Duration). Frames with inbuilt DR can go quite a bit farther than that, but even Banshee or Gyre can facetank with HCAB strats.
But I'm Inaros or Lavos
This section is theoretical, since I don't have Trickery.
Desiccate, Ophidian Bite, and Dagger heavy attacks force finishers, so you could use this with Arcane Trickery to stay invis. Otherwise possible helminths are Resonator (from Octavia), or Shooting Gallery (from Mesa) + Muzzle Flash augment.
Good insight! (Also, nice to see you here!)
How do you feel about Operator/Drifter? There's something to be said about exploiting the one thing you always have direct control of, being your operator loadout, in a mode where success can have RNG as a heavy factor. Especially with nice CC options like Magus Lockdown.
I can't really speak from experience as to Operator/Drifter survivability techniques. On paper, Vazarin has a mix of CC and Protective Sling, and Naramon has two CC options. Magus Cloud also benefits Protective Sling and Sling Stun. And then like you said, Magus Lockdown is extremely powerful and reliable CC.
That said, executing Operator abilities can be a challenge on any frame that leaves abilities active, as the 10% of damage that gets through while you're outside the frame will oneshot it while you try to get your CC off.
Still, definitely something interesting to try.