The Searing Wastes can be described as a wasteland that is incredibly hot and uncomfortable to traverse for humans.
Story
Escha and Logy are first dispatched to the Searing Wastes in Term 6. They are tasked with gathering materials and eliminating monsters there throughout Terms 6, 7, and 8.
As Escha and Logy are looking for a power source for their new airship engine, Wilbell refers them to the Fire Lord who resides at the Fountain of Flame. The Fire Lord gives them a suitable material after Escha and Logy help replace the Spirit Gem at its altar. If Wilbell (available through DLC) reaches Friend Level 60, she is able to form a contract with the Fire Lord and have one of her skills upgraded.