Defeat enough Red Legion troops in the Gulch to synthesize a new code that will enable access to the substrate.
- Once you begin this quest, you will be instructed to find and kill off a number of Cabal in the Gulch.
- Defeat Cabal in this area have a high chance to drop the Security Data Fragment.
- When you have collected 3 fragments, you will be contacted by Devrim Kay and Cayde-6.
- It will be time to head into the tunnels at that point.