It may be different depending on your oath. One thing which works for all of them I believe (Oath of the Ancients for sure) is to kill Scratch.

"He that can smile at death, as we know him. Who can flourish in the midst of diseases that kill off whole peoples. Oh! If such a one was to come from God, and not the Devil, what a force for good might he not be in this old world of ours."
-Bram Stoker, Dracula