History of Assistant's Assistance

How to complete

Part of the Vexcalibur exotic mission triumphs (Season of Defiance), counting toward the Queensguard seal. Uncover the secret entrance to //node.ovrd.AVALON// (reportedly a cave guarded by a Harpy in the European Dead Zone) during the exotic quest.

The Bungie forums report that the triumph can fail to register even after finding the cave; if so, retry and check the Triumphs tab. Exact route is not documented in sources I could open.