The Granum Void is unlocked upon finishing the The Deadlock Protocol, a quest available from your codex. Playing the minigame associated with these mystical arcade machines can get you some nice rewards, including high-tech weaponry, cosmetics or even Protea.

Granum Void access is granted by interacting with the golden hand statues found on Corpus ship missions (like Fossa on Venus) and paying a Granum Crown (dropped by treasurers on those same maps) to open a portal for your group. Higher level treasurers will drop a higher grade of crown that opens a higher difficulty Granum Void that gives different rewards.

When inside, you’ll have a limited time to kill as many of the floating spectres as you can, with the maximum reward being available at 75 plus 25 per extra squadmate. As such, you need to kill very quickly to get the maximum rewards, including weapon parts and Protea components.

• Xoris: Obtained as part of The Deadlock Protocol, detonating this glaive mid flight will deal damage in a decent area – it also accumulates charge based on kills made in the Granum Void, and will consume this to further boost the explosion. I found that equipping Killing Blow and Whirlwind helped a great deal, and modding for gas or corrosive dealt with the spectres.
• Nuke: The other approach is to take something like Mesa or Volt, use their fourth ability and gun down/electrocute everything in a large radius, effectively bypassing this mini-game. Protea can use her turrets to do the same thing. With rank 9 Piloting in your Railjack Intrinsics comes the option to have a crewmember on call – they can be summoned into the Granum Void to help you kill spectres.

Now, the Xoris does take a bit of practice to get the rhythm – aim, launch, detonate in crowd. If you can consistently tag three enemies in the blast, you’ll be able to keep using the fully charged explosion and scythe through the spectres. I also found that focusing on freeing the stranded Solaris was a bit of a trap, despite the bonus time they give you. Fighting beside them let me clip them with fully charged detonations, passively freeing them. Note that any normal mission will continue while you’re in the Granum Void, which can be tricky in a survival mission.

The rewards obtained from the Granum Void vary depending on both a) the type of Granum Crown used and b) how many spectres you kill. Notably, killing enough spectres to get a reward when using a Zenith Crown can cause a candidate “Sister of Parvos” to spawn during the current mission – kill her and she will be revived as an enemy you can hunt down for a custom weapon and a robotic dog!

The final thing to remember is that this is a quick game mode, so don’t get frustrated if you fail – a simple low-level capture mission on Phobos (Skyresh) will let you get another attempt on the lowest level to practice, and a treasurer will spawn after a couple of minutes so you can easily get another Granum Crown.