How to complete Vox Obscura and get Dead Messenger

Once the Code Wardens are defeated, head to the ramp with a huge circular door at the bottom of it, but make sure you blast the Scorpius machinegun turrets and Colossus blocking your path. They may be basic red-bars, but the number of Scorpius guns can catch you off-guard if you’re too hasty.

Beyond the door is the big boss fight with Qabix, Insurgent. Qabix is a standard three-phase boss. You can take down the first chunk of his health bar without trouble, but then you need to take out three more Psion Commanders in bubbles, similar to the Code Warden protectors, who are located on the north, west, and east sides of the arena. Again, a Hunter with invisibility can make this process very straightforward, or else just blast their allies before going for the melee kill.

With his protection gone, Qabix is open to more damage. Take him down to his next health pip and then repeat your circuit around the room for another trio of Psion Commanders, before unleashing whatever you have left to finish off Qabix and complete the combat phase of Vox Obscura.