History of Coordinated Efforts

Coordinated Efforts is the Witness encounter challenge in the Salvation's Edge raid. The game text only says to complete the "Coordinated Efforts" challenge; the objective below comes from Shacknews.

How to complete

1. Reach the Witness encounter with a full fireteam of six.
2. You must break all of the Witness's glyphs (the buttons) within a few seconds of each other.
3. Easiest method: get all six Guardians the Glyphbreaker buff so each player breaks one button at the same moment.
4. Alternative: three strong players each pre-damage two buttons, then finish both nearly simultaneously.
5. Tip: breaking the buttons in quick succession means only one Subjugator spawns instead of six, so the encounter is easier anyway.

Rewards

Completing the challenge grants extra raid loot and increases the drop rate of the raid Exotic Euphony. It is part of the Salvation's Edge triumph set; the exact seal was not confirmed in the sources I opened.