Kill any 9 invaders from the Firelands in the Regrowth or Sethria's Roost.
Of all of our tasks here in Hyjal, the most pressing is simple: destroy these invaders. The very nature of fire is that it is all-consuming. Lower your defense for just a moment and it will destroy everything in sight.
Kill any of the fiery invaders you find. Every enemy defeated purchases more time for Hyjal.