Destroying the Communications Array in the Horn of Abolition takes top priority. However, you can find collectibles like Audio Logs to find more information about Escharum and the Horn of Abolition area.
The Spartan Core is to the southwestern part of the region. Go north and jump to the roof of the building to the right. You will see an entrance and the Spartan Core is on the ground when you land.
Banished Audio Logs
In the same area as the Spartan Core, go to the first building on the left and jump up into the roof to get in. Go to the lower level and you will see the first Banished Log near a table.
Go outside the building and climb the hill. Enter the building to your left and go all the way inside until you see a weapon rack, the second Banished Log is next to it.
UNSC Audio Logs
Go to the southwestern part of the area and climb the mountainside. You will find a cot with the first Audio Log on top of it.
The second Audio Log is in the northwestern part of the region. Before you enter the ruined building’s area, you will see a rock near the road. The second Audio Log is on top of the rock.