The Host of Suffering was a death knight order who succeeded the death knights of Acherus who were, for the most part, freed of the Lich King's will after the Battle for Light's Hope Chapel. Under the command of the Lich King, the Host was based in Malykriss: The Vile Hold, a Scourge necropolis under construction in Icecrown. Had it been completed, their necropolis would've been all but indestructible.
Orbaz Bloodbane, one of the last powerful remaining death knights of Acherus, was their leader and selfproclaimed "Hand of the Lich King". Like in Acherus: The Ebon Hold before, there are three different death knight masters, each one teaching the adepts a different path of ability.