From WoWWiki

Shadowbreak Ravine is a well-hidden area found in the mountains southeast of Magram Village in Desolace. This area is a haven for Burning Blade cultists. It holds several structures including giant mushrooms and a summoning circle with giant chains.

There is only one quest that makes use of this area, Reagents for Reclaimers Inc., the Ley Hunters drop Felhound Brain, as do other felhounds in Desolace. Some speculate this subzone was intended to be used in the warlock level 40 mount quest as you can find some neutral level 40 felsteeds there.

Subzones of Desolace

Bolgan's Hole • Ethel Rethor • Gelkis Village • Ghost Walker Post • Kodo Graveyard • Kolkar Village • Kormek's Hut • Magram Village • Mannoroc Coven • Nijel's Point • Opal Ridge • Ranazjar Isle • Realm of the Harpies • Sar'theris Strand • Sargeron • Scrabblescrew's Camp • Shadowbreak Ravine • Shadowprey Village • Spearhold • Tethris Aran • Thunder Axe Fortress • Valley of Bones • Valley of Spears • The Veiled Sea