From Titans (Book #4) by Mary Ting
Everyone is searching for Mason.
Zeus sent Hermes, and the Oracles have used their magic, with no success. A sparkle of hope arises when Eris, the goddess of Chaos, sends an invitation to her wedding engagement party. She’s holding Mason hostage, and Skylar and her friends only need permission to enter Eris’s world to rescue him.
At the party, Eris gives them one condition: In exchange for Mason, they must travel to the Land of Reverse and bring back the bottle of gold water King Midas used to wash himself free of his gift. Further chaos follows when Eris not only sets up a hunt in the Labyrinth of Crete, but makes a bargain with the Titans she rescued.
The Titans possess power more than anyone anticipated, and Cronus is hungry for revenge after his own children locked him up in Tartarus. No one is safe. Not even the humans.