Deathwing is coming - and he will kill you. (spoiler alert!)
We're all aware that with the coming World of Warcraft: Cataclysm expansion, Deathwing the Destroyer will return to Azeroth and rend it asunder. What we've just now learned, however, is that not only will Deathwing wreak a world of hurt upon the face of the land on launch day, but it appears that he will be roaming Kalimdor and The Eastern Kingdoms ravaging zones with deadly fire until he is stopped.
Blizzard poster Zarhym writes:
One of Azeroth's oldest adversaries will soon tear through the Elemental Plane to reforge the world in flame, but this foe won't be conducting his reign of terror from the confines of a castle or lair. Deathwing is a destructive force the likes of which adventurers have yet to see in World of Warcraft, and his appetite for devastation can only be satisfied by the shattering of the world. Following his explosive escape from Deepholm, Deathwing will cast a deadly shadow over the people of Azeroth as he wreaks indiscriminate havoc across the land.
Once free to terrorize the world, Deathwing will randomly choose territories in Azeroth to attack each day until his ruinous reign is brought to an end. A blackened sky will be the only warning before every living creature caught in his approach is consumed by his terrible fire. The unfortunate victims of his malice will receive a rare Feat of Strength... as well as a repair bill and corpse run.
When Deathwing returns, you'd best keep your eyes on the skies.
Zarhym also posts that "There is very little warning once he decides to strafe a zone. If you're not in the zone already, you have virtually no chance of sacrificing yourself to his flame. If you're in the zone, you're almost definitely screwed."
So it appears that once Cataclysm hits, Deathwing will periodically raze a zone to the ground, killing any creature, critter, NPC, or player in his path. There will also be a Feat of Strength associated with dying to his flame, comically called "Stood In The Fire".
The achievement will be a Feat of Strength "since it won't be available forever," says Zarhym, which makes me think that it will most likely continue until the server-first kill of Deathwing, barring some type of re-imprisonment questline in Cataclysm. It should be interesting to see how it all pans out, whether you're a seasoned character or a brand new toon. Remember, Deathwing doesn't care what level you are.