User blog comment:Orion76/Terraria Ideas: World's End Mode/@comment-108.32.69.180-20120217230433

If you need the Edge of Life to kill the Demonite Skeletron, and the only way to get the Edge of Life is to have demonite crystals, and the only way to get demonite crystals is to kill the Demonite Skeletron, its impossible to get the Edge of Life without killing the Demonite Skeletron first, but its needed to have the Edge of Life before beating the Demonite Skeletron.