Würm of the World's End

The story goes like this

When the elf Torik wove his dragons out of the ether, it was in the shape of the oldest foe of the elves he shaped them. The Würm of the World's End sleeps, dreaming dark dreams from deep in the soil, buried beneath a great tree far in the west. When the elves buried this foe before the age of man, they took from it the great fangs that lined its maw, and crafted from them weapons to safeguard its burial. Tales say the dragon's dream are what give children nightmares, and what inspire young elves to set out into the world to quest for the teeth of the slumbering one. The Teeth of the Dragon are legendary among the elves, though questions exist among the scholars if they are real or simply folklore, passed down the thousand and thousands of years the elves have walked this world.

The legends say if the teeth are all gathered, and placed in their sacred spots around the tree of this world, the roots will wither, and once again the Würm of the World's End will slumber no more, and bring about the end of all the planes that the elves have ever walked or dreamed to walk.