The Triet Ruins is an area buried within the Triet Desert in Tales of Symphonia. The ruins lie near the desert town Triet and house the Seal of Fire, where the Summon Spirit Efreet is fought during the story.
The Triet Ruins once existed as the city of Triet, and the current Triet is actually the second rendition of the city. In the past, there was a failed Chosen in Sylvarant named Nova, who was involved in the destruction of the old Triet. Records in the Tower of Mana indicate that, while Nora was releasing a seal in Triet, one of her priests became violent. This resulted in Cruxis releasing the "wrath of god" upon the city, and it is now known as the Triet Ruins, while a new Triet was built nearby. The Seal of Fire is still located in the ruins, however, and the event eventually came to be known as "Efreet's Hellfire".
Tales of Symphonia
Lloyd Irving and his companions first travel to the Triet Ruins in order to reach the first seal in the Journey of Regeneration. Outside, the group defeats a group of monsters, and it is here where Kratos Aurion teaches the others some self-defending techniques: Guardian for Lloyd, Damage Guard for Colette Brunel, and Force Field for Genis and Raine Sage. While analyzing the outside of the ruins, Raine discovers the Oracle, which Colette proceeds to place her hand upon, revealing the entrance. Inside, the group makes use of the Sorcerer's Ring, igniting torches within the walls in order to shift the layout of the dungeon. Upon reaching the seal, the group is forced to face a guardian trio of Fire-based foes. Afterward, Remiel appears and bestows angelic power to Colette, granting her wings and first Angel Skill, Angel Feathers. Colette collapses upon exiting the ruins, forcing the group to set up camp. Well aware of Remiel's words of trials and tribulations, they decide not to seek medical help, accepting the condition as a normal part of the transformation.
Later in the story, after forming a pact with Undine, the Summon Spirit of Water, the group has the option of returning to the ruins for Sheena Fujibayashi to form a pact with Efreet, the Summon Spirit of Fire. By forming this pact, Sheena gains the Summon: Fire and Sylva Seal: Fire artes, as well as obtains the "Garnet" ring. If the group defeats Efreet after they obtain the Rheairds, Celsius, the Summon Spirit of Ice, will appear and speak with Efreet. She exhibits animosity toward him, mainly due to the fact that they are harmful to one another.
Tales of Symphonia: Dawn of the New World
Although the ruins were damaged due to the rampage of the Giant Kharlan Tree, an area is available to explore in Tales of Symphonia: Dawn of the New World. However, since the Centurion of Fire, Ignis, is currently in a core state, the ruins are blanketed by snow, similar to Triet. Emil Castagnier and Marta Lualdi journey with Raine to the ruins in order to investigate Ignis's core. Upon arriving, Raine is shocked at its current state. Inside, they meet Genis, who explains that he is attempting to unveil the climate change mystery, as well as searching for Lloyd. They begin discussing the possible locations of the Centurions' cores when Raine comes to the conclusion that they are in the same place as the Summons Spirits were two years prior.