Fact
Wailing Caverns (Barrens, the natural Horde dungeon for your level range) drops the five 'of the Fang' / Embrace of the Viper pieces. Wowhead's datamine lists 2pc Intellect, 3pc Attack Power, 4pc 'Embrace of the Viper' and 5pc 'Dream Venom'; wearing all five unlocks Serpent Form. Worth farming as a collectible even if you out-level the stats; transmog can keep the look later if you turn it on.