Classic Anyone know what's up with the Deathbringer achievement?

The achievement itself doesn't seem to be in game (unless it's a feat of strength?) but the mount Deathbringer's Flayedwing is and references the achievement. The Many trials of Zo'Sorg achievement (required for Deathbringer) also doesn't seem to be in game. Is this a time gated thing or is it just cut? via /r/wow https://ift.tt/2Joonrx