Eris provides the Guardian with news that Calus had roused the Lunar Pyramid.

Eris Morn: It is the beginning of the end. A dormant herald of the Collapse stirs in its lunar tomb. Where once we banished the Nightmares, a new terror rouses them from their slumber. Calus. The emperor of the Cabal, betrayed by his own daughter and cast into exile... now obsessed with a Voice calling to him from within the Darkness. But we will not cower in fear of Nightmares. We will do as Guardians have always done. We will rise... to meet the enemy. And confront our darkest fears with open eyes.