They are an amalgamation of lesser spirits bound together by the Twilight's Hammer cultists' magic.
The rebuilt flameseer's staff will give us enough power to shatter its bonds.
Destroy the smaller elementals once you've broken up the more dangerous large ones.
Rewards
You will receive: 5 90
Progress
Is it done, <name>?
Completion
Well done, <name>. This will help us turn the tide against the enemy.
Notes
Head out to a burning area. Contrary to what the flavor text is on the staff, find a Blazebound Elemental and use the Flameseer's Staff on it. It will die, shattering into ~6-9 Unbound Flame Spirits, each with ~1500 health. Do a quick AoE to take them all out.