Bohu is a Dawn Titan, and also an Elder Evil. It is referred as ''The Entity Divided'' because its true form lies in the Far Realm, while it manifests its physical form in the Material Plane as essentially a walking mountain of indestructible eldritch crystal and stone.
Bohu is also capable of creating a mobile projection it utilizes to deal with threats. The projection is known as "Tohu." Tohu is incredibly powerful, but can be destroyed, though Bohu was capable of re-creating it if it was.
Before the creation of the Hawthorne Guild, Irisen, via Wish, her blood magic and the sacrifice of Hawthorne, her friend, sealed the titan. In some way, she was acting as the seal, and because of the actions of different factions in 1494 DR, she was weakening, thus the seal was weakening.
‘’This was the true body of the titan Bohu. The mass was dormant and inert and as they later came to learn, it had a dimensional connection to an area within Realmspace on the world of Toril, situated in the Greypeaks: within Split Tooth Mountain, where Irisen Rhuvali had sealed away the Titan.
Bohu in truth was an entity divided, with its true form and consciousness residing in the Far Realm and outside the known multiverse, while it manifested itself physically within the cosmos and only capable of influencing the cosmos through the point at which its presence met the multiverse. This point was Bohu’s core, a lens through which its physical form was projected, and the means by which it was capable of interacting with the multiverse at all. Irisen Rhuvali had utilized sympathetic magic to lock away the physical form of Bohu on the Material Plane which in turn rendered it inert and dormant in its home reality in the Far Realm as well. This manifested itself in massive bindings across its true form in the Far Realm.’’
In early 1494 DR, Bohu was able to break free from its seal. It began marching towards Hellgate Dell. It has been theorized Bohu’s objective was to use the latent magic of the area as a means to accelerate the spread of void corruption across Realmspace and as a way to utilize the energy present to facilitate pulling its true form from the Far Realm and into the Material Plane.
During 1494 DR, the adventurers of the Hawthorne Guild were able to seal the titan Bohu once more.
For more information, read the following document:
https://drive.google.com/file/d/1Qnu2bk8QEcfK18wyVVkcNEY1j3EQhdSh/view?usp=sharing