The Eternals are an army of immortal spirits and champions in the service of Balthazar. They are his forces inside the Fissure of Woe, locked in an everlasting struggle with the Shadow Army of Menzies. Unlike the dark appearance of the Shadow Army, the Eternals are glowing spirits.
Despite the fact that they are immortal, they can be killed if your party lures hostiles near their position, and if this happens, your party will be immediately expelled from the Fissure.
For a list of all units in the Eternal Army, see: Category:Eternals.