Neltharion's Lair: Potent Powder

Objectives
Acquire Precipitating Powder in Neltharion's Lair and bring it to Deucus Valdera in Dalaran.
 * Precipitating Powder
 * Dargrul slain

Description
I've heard rumors that the ancient drogbar collected powder from the residue of dragon's breath. If it's true that Neltharion's Lair lies somewhere below us, it seems a likely source.

Go there and try to find a replacement for my powder.

Rewards
You will receive:
 * 15,900 XP

Progress
What have we here?

Completion
You... you found some? I'm impressed, and that doesn't happen easily I'll have you know.

Now let's see what exactly it was that you found...