The Gral of Erebos is a mysterious location that appeared at the climax of Trails of Cold Steel III. It is where the corrupted Holy Beast, the Nameless One sleeps, as well as the missing Primal Ground.
This dungeon's structure is circular, and is divided into strata. At the end of each stratum, a boss encounter occurs, which is composed by a group of various adversaries:
- Arianrhod and McBurn are fought on the top level: Laura, Emma, and Gaius are required to be in the party.
- Azure Siegfried, Kreuger, Rutger, and Shirley are fought on the middle level: Alisa, Fie, and Sara are required to be in the party.
- Claire, Lechter, Millium, and Rufus are fought on the lower level: Elliot, Jusis, and Machias are required to be in the party.