The Crystal Kingdom by Carey Pietsch and McElroys

A desperate call for help interrupts holiday celebrations at the Bureau of Balance, and sends Taako, Magnus, and Merle on a high-stakes mission to find and Reclaim a fourth deadly relic: a powerful transmutation stone, hidden somewhere in the depths of a floating arcane laboratory that’s home to the Doctors Maureen and Lucas Miller. An unknown menace has seized control of the stone and is using it to transform the lab into a virulent pink crystal that spreads to everything it touches It’s only a matter of time before this sparkling disaster crash-lands but in order to find… Read more.