This was the name of a sadistic project implemented by The Scourge prior to their attack on Quel'Thalas. Although the particulars are lost to history, the basic premise was well known:
The capture and systematic torture of High Elves to determine the limit of their endurance.
Over several years, Scourge raiding parties would abduct any High Elf unlucky enough to cross their path. The elves were then shipped, in chains, to Northrend and taken to an underground dungeon known as Dreadmire.