This item is acquired in-game. See its sources below.
In the Appearances collection, Maddening Dredged Leather Leggings is listed as Profession. Appearance ID: 40917. 2 other items wear the same appearance:
Read from the World of Warcraft client build files.
Leather is the armor type Demon Hunter, Druid, Monk and Rogue wear. With Agility or Intellect, Maddening Dredged Leather Leggings suits Assassination, Outlaw and Subtlety Rogue; Brewmaster, Mistweaver and Windwalker Monk; Balance, Feral, Guardian and Restoration Druid; Havoc, Vengeance and Devourer Demon Hunter.
Maddening Dredged Leather Leggings is part of the transmog set Treacherous Schemer's Leathers (Rogue, Monk, Druid and Demon Hunter only). The other 16 pieces:
Maddening Dredged Leather Boots
Darkheart Robe
Stygian Guise
Pauldrons of the Great ConvergenceGibbering MawSpaulders of Aberrant AllureTortured Fleshbeast Cuirass
Chitinspine Gloves
Bracers of Dark ProphecyOnyx-Imbued Breeches
Cord of Anguished CriesBoots of Manifest ShadowBelt of Braided VesselsMacabre Ritual PantsCorpuscular Leather GreavesWristwraps of Volatile PowerBuilt from the World of Warcraft client build files and recorded Auction House snapshots.
Maddening Dredged Leather Leggings is not traded on the Auction House, so it has no Auction House price. It is acquired in-game from the sources listed above. This page collects its first-party game data (identity, effects and where it comes from) from the official World of Warcraft client build.
TheWoWDB