Challenege of the Elders
From Destiny 1 Wiki
“Holders of the Elders' Sigil may join with two other Guardians to face the Challenge of the Elders.” ― In-game description
Challenge of the Elders is a Prison of Elders challenge mode added in Update 2.2.0. Entrance to the activity requires an Elders' Sigil, which can be purchased from Variks. Fireteam matchmaking is disabled.
