The sacrificial pits of Azjol-Nerub were used long ago to sacrifice enemy forces in exchange for success in battle. Undead forces may be sacrificed at this location to call forth a shade, an invisible wraith capable of spying on the enemy, detectable only through magic. (W3Man 44) Sacrificial pits are now used by acolytes of the Scourge who wish to serve as the eyes and ears of Ner’zhul are capable of shedding their bodies and taking on the forms of invisible Shades. (W3Man 39)