Cultist Hunt

 is a side quest and is begun by talking to Valentina and Federico in the westernmost part of the Kupeleleza. Throughout the quest, the player is asked to find and defeat the cultist group hidden at Sons of Crystal in the eastern part of Corrupted Badlands and talk back with Valentina.

Objectives

 * Find the Crystal Temtem cultist.
 * Report back to Valentina

Guide
After defeating Valentina and Federico, the player can talk with them to start the quest. If they have defeated all the Sons of Crystal, they will complete the quest. Otherwise, they must travel there through the Xolot Reservoir and Corrupted Badlands to fight them. After defeating all four, they return to Valentina.

Items

 * Sweatband, a Gear kept as a reward

Story
The player encounters Valentina in western Kupeleleza, in need of a well-trained tamer and a stranger in Tucma. She introduces herself as a PhD Arbury student, and her supervisor as Professor Víctor. Her thesis has made little progress, and her fieldwork in Tucma has also been slow. The thesis's topic focuses on ancient cults centered around Temtem worship; their ancestors worshipped powerful Temtem, and in some places in the Archipelago, these cults still persist. She references the Sea Queen as a Denizan example. The monks in the hills of Cipanku cooperated with her, but she has been unable to locate the Brothers of the Shard for an interview. Her sources point to the Corrupted Badlands, but beyond that eludes her. The player agrees to help.

After infiltrating the group, defeating them in combat, and learning the details of their practices and beliefs, the player returns to Valentina. They spill the details and Federico writes it all down. The player makes a remark that Federico is a puppet, but she ignores them and gives them a reward. With no pansuns, she gives the player a sweatband, and invites them to come and see them at the university.

Trivia

 * The Cultist fights can be particularly difficult, as almost all of them have Bunbun or Mudrid, which have earth techniques that are super effective against crystal Temtem. It can be wise to target these Temtem first, in order to avoid them quickly wiping your team.
 * A good way to easily win these fights if you don't have good Crystal type Temtem is to capture a full team of Bunbun in the Mines of Mictlan and to spam the Mud Shower Ability in every single fight.
 * Defeating all the members will give you access to the Crystal Shrine.
 * The group is called the Brothers of the Shard.