The life Preserver is and invisible barrier that surrounds the High Elven City of Mistyvale. The barrier was created over 2000 years ago by the arcane Elves that escaped the tyranny of the Titans. The Life Preserver over the centuries has been reinforced and it became a powerful shield against evil forces.
The survival of Mistyvale rests on the continued protection from the Life Preserver. Should it fall, Mistyvale will be quick to follow.