[Steel Charge] or [Swift Momentum] but you lose combo stacks on heavy attacks.
Duration on [Nyx] = Absorb drains energy slower. So, you could replace something with Primed Continunity and it would be SLIGHTLY less, but still this is a 1 energy per second build already.

Shorter missions: Helios - Deconstructor - all Gladiator mods = Sentiniels are invulnerable when Absorb is active, this gives you more crit for your melee. I use Healing Return on [Deconstructor] mostly, but that mod is not needed for this build.
Longer missions: [Dethcube] (With Energy Generator mod) - With Deth Machine Rifle - Equip Vigilante Mod set, and ALL PUNCH-THROUGH mods to hit most targets to keep orb drops up like crazy.

Nyx Naramon - Use Heavy sword and use Leap attack stance Tempo Royale to jump 10M+ and swing away at targets... Beserker, and Bloodrush recommended. Combo Counter chance mods if you plan to use more heavy attack swings and swift momentum.

Use stat stick primary/secondary to stack for Condition Overload shots on tougher enemies.

Originally, I was doing this build with the Paracesis and it looked like [Nyx] was doing Cartwheels with the jump attacks so hence the name.