The Caged Grambia

Gramby, the son of the God, one day left heaven for his own sake, created a magic land called Grambia, which could not be seen by other people on earth.
Gramby had three assistants called Kesla, Ackley and Skidder, who he believed would lead Grambia well after his death. But one day he realised all he expected was wrong and he was too old to conquer his assistants. And he found out that bad mages would get out of Grambia and slay the normal people on earth.
Before his death, he cursed Grambia, that if one left Grambia, he would melt and die.
But there was a prophecy.
One day there shall be someone who would save Grambia from the curse.