Confront the Lich King.
I be havin' many rivals when it comes to claimin' souls. But it takes some serious mojo to do to Vol'jin what ya describe. Dat kind of power smells of old magic. Icecrown. It be more dan a pretty throne. It be an anchor dat holds dis world to da next, ya might say. I gonna open a death gate, and ya can go through and ask da Lich King if he be treadin' on Ol' Bwonsamdi's ground.