Xanthar was chosen to find a way to save his planet from exhausting all of its resources. He is abducting alchemists to take back to his home planet. Using alchemy, he hopes to save the planet, while imprisoning alchemists to learn their techniques. He has also discovered donuts, which he also plans to bring back to his people.
As an Event Alchemist, Xanthar does not have traditional prize cards. Instead, rewards are based on tiers, as described by the Invasion Event page, as well as from Portal Keys/Diamond Spins, as denoted on the Diamond Spin Rewards page.