Jeff is the real sacrifice, and Derek is the actual leader of the coven with Miranda as his co-conspirator to trap Jeff and make him voluntarily come to the sacrifice. Derek and Miranda mock Jeff and Derek kills Jeff who realizes the full extent of the plot and his betrayal, but is too late.
Jeff is the actual victim, and Derek is the true leader of the coven with Miranda as his accomplice to lure Jeff into the sacrifice. However, Derek ultimately kills Jeff, who comes to understand the full extent of the plot and his own betrayal, but it's too late for him to escape.