Caustic Venomfang

Complete Hagar's Invitation and What Lies Beyond the Fog, then progress the Vaults of Atal'Utek: Certain Doom introduction until the Altar of Corrosion and indoor public activities are available. Flying is disabled inside the Vaults.

Enter from Gate of the Serpent's Eye at 43.72, 44.19, Western Fang at 31.29, 64.18, or Eastern Fang at 45.67, 64.90 on Coiled Isle map 2512. Use Amani Windcallers and the zone's movement powers after entering.

Complete Temple Patrols as they appear. Patrol completion builds toward Temple Strikes; completing two Strikes triggers a larger Temple Incursion and boss. Venomous Hunt and the Corrosive Spirit milestones at 5/10/15/20 Corrosive Souls increase coin income, while Corroded Grounds adds coins to gathering.

Keep farming until you hold 10,000 Corrosive Coins. The currency is also spent on Altar progression, pets, transmog, and decor, so buying those first delays the mount. The correct price is 10,000—not the 1,000 value shown in an early roundup table.

Inside Vaults map 2509, travel to 51.2, 62.4 beside the Altar of Corrosion. Interact with the vendor object named Skull of Er'inye and verify that the item shown is the green Caustic Venomfang.

Spend 10,000 Corrosive Coins, use the mount item, and verify Caustic Venomfang in Collections. Its appearance is a long, bright green venom serpent with potent caustic effects—not the red Glory reward or blue Tokka vendor serpent.