One of the two dailies to unlock the Armory portion of the Shattered Sun Offensive on the Isle of Quel'danas, this quest will send you on a bombing mission down the Dead Scar, the giant strip of dead land that marked the Scourge's march to the Sunwell. There's still scourge there, but your target will be the Demons fighting them, in hopes that your attacks will disrupt their efforts to keep the Armory by drawing more and more of them away and to the Scar itself.
You'll get the quest from Battlemage Arynna in the new sanctum building. She'll order you to kill 2 Pit Overlords, 3 Eredar Sorcerers, and 12 Wrath Enforcers, provide you with some Arcane Charges to drop on them, and send you to Ayren Cloudbreaker, who is located back by the docks where you first land when coming in by gryphon or bat.
From there, talk to him to get your Dragonhawk. The Dragonhawk will fly on a predetermined course. You'll first pass some of Kaelthas' archers and fly over the Naga and Murloc villages before you hit the Dead Scar. Once there, you'll need to be on your toes, especially if there's other people trying to kill the demons. You'll see the demons both on the ground and on the balconies and ramparts and bridges to the sides of the Dead Scar. The Wrath Enforcers often come in packs, and will generally die in one hit, but the Eredar Sorcerers and the Pit Overlords may take 2 hits, so you'll have to watch for them to show and quickly hit them before you fly back out of sight. Once you hit the end of the Scar, you'll get a brief glimpse of Brutallus fighting Madrigosa before you turn around and fly back over the scar, giving you one more chance to hit a few demons.
If you don't have your demons killed after the first run, you don't have to abandon the quest to try again. Instead, you can simply talk to Ayren to be sent on another pass. Luckily, after the first 2 or 3 tries, you should probably get the hang of it enough that you'll do it in one pass, assuming there's enough demons to go around. If nothing else, it's sort of nice not to have to dodge Kaliri or Fel Cannons.
Once you have your demons, return to Arynna. You'll get 9 gold 10 silver for your troubles, and credit for your server towards the next step of the offensive. Plus, the fun of having totally ridden a Dragonhawk. Once this phase of the offensive is unlocked, this quest will be renamed "The Air Strikes Must Continue." For further information, you can also check this quest on Wowwiki and Wowhead.