Den of Woe The Den of Woe is an optional dungeon in " Final Fantasy X - 2 " . It is a hidden cave in the Mushroom Rock Ravine sealed with special spheres . Although Den of Woe is a sidequest , unlocking and entering the Den is necessary for achieving 100 % completion . Completing Den of Woe gives the player Episode Complete . Story . The Den of Woe is where the spirit of Shuyin has dwelt for 1 , 000 years and the pyreflies within have become imprinted with his hatred and begun acting on their own volition . Rumors began circulating that people who entered the den witnessed illusions of a colossal machina . During Operation Mi ' ihen Maester Wen Kinoc sends in a group of aspiring Crimson Squad members , an elite branch of the Crusaders , under the guise of a final test to enter the force , his true reason being investigating the rumored illusions . Shuyin ' s spirit possesses the Crimson Squad candidates and they slaughter one another , with only one group escaping : Nooj , Baralai and Gippal and their sphere recorder Paine . As they fail to provide any useful information on the visions of a giant machina , Kinoc orders them executed to cover up the failure but the four escape . Kinoc orders the den to be sealed with magic . Two years later the Gullwings stumble upon the den while heading to the Youth League Headquarters as they detect spherewaves and decide to investigate . They discover Ormi and Logos , Leblanc ' s henchmen who once worked for Kinoc , trying to open the sealed door by using various spheres . The goons flee , but leave behind a sphere , coincidentally the one that was part of the unlocking mechanism of the door : a Crimson Sphere , part of the set of spheres Paine had recorded of her group ' s progress . If the Gullwings return to the den after relinquishing the Awesome Sphere to either Youth League or New Yevon , they can meet Nooj outside the den who gives the party a Crimson Sphere . The Crimson Spheres are the records of Nooj , Baralai , Gippal and Paine ' s experiences while training for the Crimson Squad . Locating all ten spheres unlocks the door and allows the party to enter the den . They find a cave filled with the pyreflies that have kept Shuyin in a semi - corporeal state for a millennium , fueling his anger and grief . During the sojourn , Rikku and Paine are possessed by Shuyin , and he shows Yuna how he and Lenne died , and summons the images of Nooj , Baralai and Gippal to fight Yuna . Yuna dispatches the illusions of Nooj , Baralai and Gippal and breaks Rikku and Paine free from their possession and the trio escapes the cave . Enemies . There are no random encounters within the cave . All fought within Chapter 5 . < nowiki > * < / nowiki > These battles are fought only by Yuna . Musical themes . " The Crimson Squad " , also known as " Party " , is a music piece which includes vocals and drums . It plays whenever recording from Crimson Spheres are watched and acts as the location theme for the Den of Woe . The theme that plays during Shuyin ' s vision is called " Nightmare in the Den " . A piano arrangement of this theme is included on the " Final Fantasy X - 2 Piano Collection " album . " The Crimson Squad " plays as the location ' s regular background music . " Yuna ' s Ballad " plays while she is fighting Rikku and Paine .