Hello there,
Felarx is a Fully-Auto Shotgun that evolves into Semi-Auto Dual Pistols
Headshots fills Incarnon Transmutation Gauge
Evolutions:
I. Incarnon Form
II. Kinetic Baffle (-50% Recoil) or Frictionless Flight (+50% Projectile Flight Speed)
III. Evolved Autoreloader (+50% Magazine Reloaded/s when Holstered) or Mounting Momentum (Reload increases Fire Rate by +10% per shell. Resets on reload)
IV. Brutal Edge (+10% Critical Chance, +10% Status Chance) or Wracking Wrath (+20% Status Chance, -10% Critical Chance)
V. Ruptured Plenitude (On Punch Through 3 enemies: +70% Ammo Efficiency for 20s) or Devastating Attrition (for pure Status build)
- In bold are the Evolutions chosen by me, you do as you see fit
Alternatives:
- For Pure Status build, use Wracking Wrath instead of Brutal Edge, and Devastating Attrition instead of Ruptured Plenitude

Above build is great against Grineer, or Corrupted, or even Infested (just change Primed Cleanse of Faction)
or

Go Radiation + Viral
With Corrosive + Heat Primer
Enjoy!
THeMooN85