To target-farm a piece of gear, you must have the "Fully Initiated" buff, and then interact with one of the nine symbols ... Active target-loot/symbol at the start of Destiny 2 Sundered Doctrine ...

In this Destiny 2: The Witch Queen Vow of the Disciple ... Once you’ve deposited nine symbols and cleared the Obelisk, the damage phase will begin. Scroll down a bit and we’ll explain that.

Rite of the Nine features 3 dungeons, and each encounter will have players face a true challenge in Destiny 2 that might be cause for concern.

Once the Payload has received all nine spikes ... reach a room full of vertical tablets with symbols on them. This is where you'll complete the Destiny 2 Preservation mission puzzle.