Items, NPCs, quests, objects and spells of patch 1.12.1, read live from the realm itself.

Ancient Corroded Leggings

NPC	Level	Zone	Chance
Ysondre Boss	??	The Hinterlands	11.1%
Lethon Boss	??	Feralas	11.1%
Emeriss Boss	??	Duskwood	11.1%
Taerar Boss	??	Ashenvale	11.1%

Item	Count	Chance
Nexus Crystal	1-2	100%
Large Brilliant Shard	1-2	100%