This build is NOT made by me, it's originally from UltimoFive, i just put his Rest & [Rage] focused build (Mr. Sandman) recommendations on the build so it's easier to remember
Original build here

The Mrs. Sandman Build for [Equinox Prime] utilizes an Extremely Large increase to Range, a Very Large increase to Duration, an a Very Large Decrease to Strength. The Build's Flex Slot is [Vitality] and works well with putting enemies to sleep for quite some time. The point of this build is to farm affinity with stealth finishers and farm for focus with a decent radius of 14m to effect enemies. [Calm & Frenzy] makes it so enemies you kill will spread the effect to even more enemies and essentially just keep everyone asleep. There isn't more to say about this build other than, "Mrs. Sandman, bring me a dream".

Recommended Alternative Mods
First off, the Aura slot can be whatever you want it to be. As long as it benefits you and what you are during currently than realistically anything can work there. For instance [Energy Siphon] is a fantastic Aura mod to generate Energy, but if you have access to energy through other means than [Corrosive Projection] could be a better choice. You could even use an Aura Forma on her so any mod could go there and not just Naramon "Dash" mods.

Intensify - In place of Umbra Intensify if you don't have it.

Continuity - In place of its primed counterpart if you don't have it.

Natural Talent - In place of the Build's Flex Slot in order to improve casting speed. Which can be very beneficial for her considering her Third and Fourth abilities have fairly long cast delays that can doom the player based on their situation.

Calm & Frenzy - In place of the Build's Flex Slot in order to give the ability of spreading her Rest & Rage amongst enemies running towards already affected enemies.

Energy Transfer - In place of [Streamline] in the Range Focused Build. Duration doesn't matter for the fourth ability augment so using it with Duration Build isn't the best, but if you choose to do so you can.

Peaceful Provocation - In place of the Build's Flex Slot in order to give an aura that slows enemies in Night Form or to build even more Ability Strength in Day Form.

Arcane Synergy
Arcane Energize - Upon Energy Pickup, 60% chance to replenish Energy to nearby allies.

Arcane Grace - Upon Health being Damaged, 9% chance for 6% Health Regen for 9 seconds.

Arcane Eruption - Upon Energy Pickup, 100% chance to Knockdown nearby enemies.

Arcane Victory - Upon Headshot Kill, 75% chance for 3% Health Regen for 9 seconds.

Arcane Guardian - Upon being Damaged, 15% chance for 900 Armor for 20 seconds.

Arcane Nullifier - Which provides a 102% chance to resist a Magnetic Status Effect entirely.

Ending
If you guys enjoyed and liked the build make sure to give it a ⭐ to help out! To help out even more, why not check out my channel where I not only make guides and builds, but also stream games, make Playthroughs, and more!

Link for my Channel 🠖 https://www.youtube.com/c/UltimoFive

See you guys on the next guide!