Buff up, deal damage and be tanky. Shares the same polarities as her 2nd config.

This build would [Reach] it's full potential if you would invest an Umbral Forma and then drop [Nova]'s Null Star for Hyldrin's Pillage. Then you would remove Corrosive Projection, Augur Message, Augur Secrets and Hall of Malevolence for Growing Power, Transient Fortitude, Energy Conversion and Fleeting Expertise/Primed Flow. That way you would reach max damage Eclipse while having an insane Shield/Armor strip ability making you insanely tanky. The range of Pillage scales with ability range and ability duration which would benefit us. Here's a link to how that build would look like: https://overframe.gg/build/230144/

Running Growing Power and more strength mods instead of Hall of Malevolence would provide us more damage mathematically speaking than the current build setup but that would require us to invest an Umbral Forma and an Aura forma since I have another build for [Mirage] that shares these exact same polarities in order to work.

The reason why I chose Null Star is because it synergizes well with negative range while providing us extra damage reduction for survivability. If you want to you can run the augment mod Neutron Star instead of Augur Secrets so that you can recast this ability in order to reset the ball count to gain the lost damage reduction from losing your balls. With 278% ability duration you'll be getting 16 balls which results in 80% damage reduction. As long as you don't go into melee range of an enemy, you will have this damage reduction non stop.

Another thing I'd like to mention about Null Star is that even tho the description of the ability says it caps out at 90% in reality it doesn't. You can actually [Reach] 100% damage reduction with this ability but you would need a Helminths Invigoration buff that gives you +100% or +200% ability duration. If it's your 10th invigoration, you can freely apply it on this [Mirage] build and [Reach] true immortality. No form of damage would be applied to you. Here's a video of a Youtube warframe content creator explaining it: https://www.youtube.com/watch?v=Cd0isrZqmM8&t=14s .

You could also go the shield gating way and equip Brief Respite as your aura forma, run a Decaying Dragon Key and subsume [Saryn]'s Molt instead of Null Star. This ability is insta cast, fully removes all status effects from you, refreshes your shields to max which allows you to have 1.3 seconds of immortality when they are destroyed. So your gameplay would be spam casting Molt every time your shields get broken. That way you will become immortal. The ability also leaves a decoy and upon reactivation the decoy explodes dealing toxin damage which is nice for Condition Overload/Galvanized Apptitude damage stacking. The problem would be ability efficiency so you would need to swap some of the duration mods to accommodate for that.

There isn't much to say about [Mirage] as a warframe. Her Eclipse buff is really strong when it gives the damage buff, but sadly it sometimes gives us the damage reduction buff which we are not really looking for when playing her. Her clones also make any weapon in her hands even more broken resulting in any weapon being steel path viable. The problem with [Mirage] lies in her survivability which we can fix with Helminth by removing her 2nd or 4th ability. I'm keeping her 2nd because even tho it doesn't serve us much purpose in this build, it's still far better than her ultimate.

I am aware that there is a build for [Mirage] that makes her ultimate viable with the augment mod, but the damage doesn't scale to endless steel path survival since it's unreliable. What do I mean by that? Well it scales damage based off of the lightning in the area, aka it can either do 1000 or 30000 damage to the enemy. I am not here to make meme "fun" builds, I'm here to make builds that you could safely equip and run them for any content you want with ease. Please use this warframe for the purpose that she was made for, which is buff up, pull out your gun/sword and kill away. There is a niche build viable for defense/eso and maybe survival that fits the same polarity slots as this build, I've linked it below.

Since we have no healing or source of cc I run Magus Elevate and Magus Lockdown on my operator. One gives my warframe 300 health back whenever I swap into my operator and the other one leaves a mine that stuns 10 targets within 15 meter range for 4 seconds, works on acolytes. I'd say these arcanes are essential and you should seriously farm Quill Onko's and Little Duck's standing to buy them, or just get them for platinum from other players.

Arcane Acceleration is swappable for Arcane Tempo if you're using a shotgun or Arcane [Rage] if you are using a low magazine capacity weapon.

ESO(Elite [Sanctuary] Onslaught) Explosive Legerdemain Mirage 2nd config build here: https://overframe.gg/build/215797/