Deathshadow

The Deathshadow is a Burning Legion cult, presumably a part of the Shadow Council, located on Twilight Ridge in Nagrand. They are trying to stabalize one of the four dimensional gateways which Magtheridon used to bring demons from the Twisting Nether under his control.

It seems this gateway is still intact.

The Dragonmaws have orders from Illidan to send Horde players on a quest, Disrupting the Twilight Portal, in order to kill Deathshadow Agents: Deathshadow Acolytes, Deathshadow Archons, Deathshadow Overlords, Deathshadow Spellbinders, and Deathshadow Warlocks are all agents of the Deathshadow.