A strange clue connects the Cloud Striders whose memorials were destroyed: Something they refer to as "The Occlusion." What it is or why the Vex want it remains a mystery, though.
Quinn asks you to try restoring the memorial to Sedderik Assur, the Cloud Strider known as Maelstrom. She was a war hero and tactician, so engaging the enemy and stockpiling supplies seem like the next logical steps.
Defend the city by participating in patrols and public events and loot chests to begin bonding with this legacy.