Fueling the Demolishers (ID 13200)

The Cauldron of Flames is the black and red area of the map at [83,71] in wintergrasp.
There are two mobs here; Raging Flames and Flame Revenants.

The revenants are the ones you want to kill as they seem to have a 100% drop rate on the embers and I've yet to see one drop from the flames.

*edit* They aren't particularly hard to kill but they do have around 25k hp.

*Update* Yes the smaller eles drop the quest items for their respective quests but they have a rather low drop rate.

It appears you only can do the WG gathering daily quests on the day they are given, unlike the seige or kill them all quests.

i have killed 10 or so flame revenants and farmed 15 eternal fires and not 1 quest item has dropped for me >_>