Ginnungagap is a World Item under the possession of the Great Tomb of Nazarick.
Tabula Smaragdina gave it to Albedo without permission from the rest of the guild. Ainz noticed only just before the game was about to end so he let it slip by.
It seems like it can be used to destroy large areas.
- Ginnungagap is a reference to the primordial void in Norse mythology.