Why Gloom?
At minimum range on [Mesa], Gloom has a max radius of 5.4m. Gloom only drains energy when enemies enter that range and since [Mesa] is generally a ranged warframe, Gloom basically has zero energy cost while giving free lifesteal on your [Regulators]. This means you can be extra lazy and stand still in peacemaker while healing any damage taken. Furthermore, melee enemies that do somehow sneak into range are slowed giving an extra layer of protection against melee, important since shatter shield does not [Protect] against melee damage.

Do NOT rely on Gloom healing and tanking in Steel Path or endurance missions as you will almost certainly get one-shot. This is mostly for lazily breezing through non-SP/endurance missions, particularly useful in open world settings.

Exilus Flexible Slot
Primed sure footed can be Synth Reflex or Preparation.
Transient Fortitude flexible for Hunter Adrenaline/Rage

Other Helminth Options
Pillage - If using Pillage you can drop both [Umbral Vitality] and Hunder Adrenaline for [Transient Fortitude] and [Augur Secrets] to hit the 200% strength threshold to allow full armor strip in two casts of Pillage. Shields become your EHP since you have 99.5% DR from Shatter Shield + Adaptation so you don't need any health.

Regulators Build
https://overframe.gg/build/211174/