How do I complete the "The Thunder Helm" side quest in The Legend of Zelda: Breath of the Wild?

To complete "The Thunder Helm" side quest in The Legend of Zelda: Breath of the Wild, you must help the Gerudo people in Gerudo Town by completing a series of smaller quests. This quest is given by Riju, the leader of the Gerudo, after you have freed the Divine Beast Vah Naboris. The Thunder Helm is a powerful piece of armor that grants immunity to lightning strikes, making it highly valuable for exploring areas with frequent thunderstorms or fighting enemies that use electric attacks.

First, you need to speak with Riju in the throne room of Gerudo Town. She will explain that the Thunder Helm is a sacred relic of the Gerudo, but it is currently being used to protect the town from the Yiga Clan. She will ask you to help the Gerudo people with their problems, and once you have done so, she will consider lending you the Thunder Helm. There are four specific quests you need to complete, each given by a different Gerudo resident. These quests are "The Search for Barta," "Medicinal Molduga," "The Mystery Polluter," and "The Eighth Heroine."

For "The Search for Barta," you need to find a Gerudo named Barta who has gone missing in the desert. She can be found trapped in the East Barrens, near the Southern Oasis. You will need to defeat a group of Lizalfos to free her. Once you do, she will return to Gerudo Town, and the quest will be complete. Make sure to bring weapons and arrows, as the Lizalfos can be tough to deal with, especially if they are electric variants.

"The Mystery Polluter" involves investigating the source of pollution in the town's water supply. Speak with Malena near the town's water reservoir, and she will ask you to find out what is causing the water to turn green. Head to the Kara Kara Bazaar and speak with Dalia, who will reveal that a man named Bozai has been throwing hydromelons into the water. Confront Bozai, and he will stop polluting the water. Return to Malena to complete the quest.

"Medicicinal Molduga" requires you to defeat a Molduga, a large sand-dwelling creature, and bring its guts to a Gerudo named Liana. Moldugas are found in the Gerudo Desert, and you can lure them out by placing a bomb in the sand. Once the Molduga surfaces, detonate the bomb to stun it, then attack with strong weapons. Molduga guts are a rare drop, so you may need to defeat multiple Moldugas to obtain them. Once you have the guts, return to Liana to complete the quest.

"The Eighth Heroine" is a shrine quest that involves finding a missing statue of a Gerudo heroine. Speak with Rotana in the Gerudo barracks to start the quest. She will tell you about a legend of eight heroines, but only seven statues are visible. The eighth statue is hidden in the Gerudo Highlands. Travel to the Gerudo Highlands and locate the statue near the entrance to the Yiga Clan Hideout. Take a picture of the statue and show it to Rotana to complete the quest.

Once all four quests are completed, return to Riju. She will be impressed with your efforts and will allow you to borrow the Thunder Helm. This item is incredibly useful for exploring areas with frequent lightning storms, such as the Faron region, or for fighting enemies that use electric attacks. Be sure to return the Thunder Helm to Riju when you are done using it, as it is a key item for the Gerudo people.

In terms of preparation, make sure you have strong weapons, armor, and healing items before attempting these quests. The Molduga, in particular, can be challenging, so having high-defense armor and plenty of food or elixirs is recommended. Additionally, for "The Eighth Heroine," having the Sheikah Sensor upgraded to detect treasure chests can help you locate the hidden statue more easily.

Common mistakes to avoid include not bringing enough resources for combat, especially against the Molduga, and not thoroughly exploring the Gerudo Highlands for the eighth heroine statue. It is also important to complete all four quests before returning to Riju, as she will not lend you the Thunder Helm until all tasks are done.

Advanced techniques for these quests include using stealth to avoid unnecessary fights, especially in the desert where enemies can be numerous and tough. For the Molduga fight, using Urbosa's Fury, a power gained from freeing Vah Naboris, can make the battle much easier. Additionally, using the Sand Seal to traverse the desert quickly can save time and resources.

In summary, completing "The Thunder Helm" side quest involves helping the Gerudo people with four specific tasks, each requiring different skills and strategies. By preparing adequately, avoiding common mistakes, and using advanced techniques, you can successfully complete these quests and gain access to the powerful Thunder Helm.