The Dracorage Mythal:
Created during the Time of Dragons by High mages of the Fair Folk, this High Magic effect tied a Faerûn-wide mythal to the King-Killer Star.
The Dracorage mythal encompasses roughly a 250,000 square mile area where the King-Killer Star is visible over Faerûn and causes all dragon and dragon-blooded creatures to slowly become more agitated and reckless, eventually becoming little more than raging beasts. This effect lasts for ten days.
Why would the wise elven high mages do such a terrible thing as setting all dragons on a rampage?