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

Bat Heart

NPC	Level	Zone	Chance
Shrike Bat Elite	38 - 39	Uldaman	38.2%
Greater Kraul Bat Elite	32	Razorfen Kraul	33.4%
Kraul Bat Elite	30 - 31	Razorfen Kraul	32.9%
Blind Hunter Rare Elite	32	Razorfen Kraul	20.0%