Upon entering the Mirage if you look around you can spot an odd looking satellite in the distance. You can look in the photos below to see what it looks like. Just fly towards this satellite until the rare nevi will appear.
For this rare Nevi it is recommended that you have your gravity kick upgraded to at least level 6, and your dodge at max for the easiest time. As it will fire a fusillade of gravity orbs with decent homing towards you upon approach, the easiest method of getting close is to position yourself somewhere above it, dodge continuously through the hail of gravity orbs, then execute a single gravity kick (or two/three, if you're feeling adventurous) gravity kick at one of its cores before retreating to a safe distance. However, do be aware that it will continue to assault you with gravity orbs until you are a significant distance from it, so in order to escape, you should use either the gravity kick or the speed fall (holding X) to escape. There are also health crystals located at various places around the Rift Plane, so you are free to heal whenever you want.
An easier but more tedious option is to lift the pieces of rubble scattered around the area with your Stasis Field, and launch them at the Nevi while flying over it. It's advised that you have your Stasis Field maxed out first before you begin the fight. Fly around the area and lift as many objects as possible. Then, fly directly over the Nevi, making sure the red orbs it keeps shooting out do not reach you. Launch all of your objects at the Nevi's core, making sure the cores are on target (inside the red circle on the screen). You'll be able to aim and hit the Nevi with little to no interruptions. Repeat this throughout the fight; it will take some time but you will eventually defeat the Nevi.
Easiest way to defeat it Edit
Head to the the second checkpoint where the first flower will direct you to. There will be a pretty big pillar where you can stasis and if you done it right, the whole pillar should cover you like a barrier, making you invulnerable to the projectiles coming at you. Always make sure you are always inside the pillar and not exposed, if not you can still be hit.
A video guide is provided here.