Shadow Council

From wow.incgamers.com

A secretive order of warlock and necrolyte magicians, founded by Gul'dan, which furtively took control of the Orcish Horde on Draenor pacifying their hunger for battle by focusing on Azeroth. In the Human year 583 they expanded the rift made by Medivh creating a Dark Portal bridging Draenor and Azeroth.

Most members were executed by Orgrim Doomhammer for consorting with demons (the Burning Legion). While Gul'dan and a few others were spared, it was more or less the death of the Shadow Council.