Where’s Oryx? The Cabal know.
You now have to assault the crashed Cabal ship on the Dreadnaught to learn what the Cabal knows about Oryx and his defences.
You start in the same place as the tank battle at the end of The Dreadnaught.
Shoot the Cabal to “weaken” them. The ship’s doors open. Fight your way in, then follow the corridors. Kill the nasty blue Cabal.
Keep going until you find a terminal marked with an arrow on the map. Scan it.
The Cabal have found Oryx and they’re hunting him in the Dreadnaught. You now need to track the Cabal. Follow the arrow to a sliding door. When it opens, kill everything. You’ll see Primius Tau’um fighting the Taken to get to the Rupture, a rift which leads to Oryx. Waste everything, both Cabal and Taken.
Jump across to take a look at the Rupture, then leap back to scan a statue. There are three of them in total.
A ton of Thrall run through. Kill some, then fight the Echo of Crota that comes through the Rupture. You can’t get through the portal because you’re not an Ascendant Hive. The mission ends when you kill the Echo.