Defend the turtle of enormous girth as it transports the Transmuting Gem. Once the attackers are defeated you can harness the gem's power to reweave the fate of your unique items that have legendary potential, either increasing it or decreasing it. The new legendary potential is rolled the same way as the legendary potential of a freshly dropped unique of that type. As such, for most uniques it is mostly likely to change the legendary potential to 0.