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

Hourglass Sand

NPC	Level	Zone	Chance
Blackwing Spellbinder Elite	62	Blackwing Lair	88.7%
Blackwing Warlock Elite	61	Blackwing Lair	87.2%
Death Talon Overseer Elite	62	Blackwing Lair	80.3%
Blackwing Technician Elite	60	Blackwing Lair	47.4%