Evidence points to the Witness weaponizing the Traveler's Light to reshape reality, just as the Traveler once terraformed planets and created Ghosts to raise Guardians. What you've seen inside the Pale Heart is only the beginning.

It believes itself to be a god of both Light and Darkness. And what are you, if not a god-killer?

The only members of your fireteam unaccounted for are Commander Zavala and his Ghost, Targe. Locate them before the Witness does.