Cadderly uses Catti-brie as a conduit to enter the Shadowfell to finish off the Ghost King. In the end, Cadderly defeats the Ghost King at the cost of his life and becomes the new Ghost King, forever reinforcing and guarding the ward containing the rift left by the old Ghost King.
Cadderly utilizes Catti-brie as a gateway to enter the Shadowfell with the intention of eradicating the Ghost King. In the end, Cadderly emerges victorious over the Ghost King at the cost of his own existence and assumes the position of the new Ghost King, thereby reinforcing and protecting the boundary created by the previous ruler.