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

Spined Bat Wing

NPC	Level	Zone	Chance
Shrike Bat Elite	38 - 39	Uldaman	38.4%
Greater Kraul Bat Elite	32	Razorfen Kraul	32.8%
Kraul Bat Elite	30 - 31	Razorfen Kraul	32.1%
Blood Seeker Elite	23 - 24	Shadowfang Keep	31.4%
Vile Bat Elite	22 - 23	Shadowfang Keep	28.8%
Blind Hunter Rare Elite	32	Razorfen Kraul	20.0%