You can think of this build as being divided into 3 sections of mods: first row is survivability, second row is abilities, third row is QoL.

Row 1:

Vitality, Redirection, and Steel Fiber, are all no-brainer choices. Repair is required since it makes your [Voidrig] practically immortal so long as you aren't burst down by a huge mob.

Row 2:

Flow, Intensify, and Streamline are also no-brainer choices. [Continuity] has limited usefulness on [Voidrig] but does help Guard Mode's energy usage. It also increase the number of Gravemines that are released if you like using that ability.

Row 3:

Thrusters and Efficiency drastically help your mobility. We forgo Refuel since the default recharge rate isn't that bad, and there are more useful mods we can take. I typically recharge whatever Engine percentage I used to get to enemies in the time it takes for me to walk around killing said enemies. Deflection helps keep you alive by quickly recharging shields during your next cast of Storm Shroud. [Rage] ensures you always can cast Storm Shroud in a pinch.

Notes:

You can swap out [Continuity], Deflection, and [Rage] as you see fit. All 3 are good but do not provide the most impactful boost to your mech out of what is selected.

Do NOT bother using [Pressure Point], [Fury], and [Stretch]. Melee and ability range do not help [Voidrig] at all in practice.

Augur sounds good on paper, but is not as helpful in practice. Until Necraweb and Gravemines are buffed or reworked, you're really not going to be using abilities all that often. Storm Shroud is used as it is depleted and Guard Mode clears things so fast you don't need to cast often.