Chac Chac is a boss from " Final Fantasy X - 2 " , found in Via Infinito on the 80th floor and a regular enemy on floors 81 - 84 ; either can appear in Oversoul form . Chac was once Lady Yunalesca . Battle . Chac is a very difficult enemy . She can petrify characters with her Stony Glare attack , which works regardless of immunities , but can be evaded with high Evasion and Luck stats . Chac never uses Stony Glare if only one character is present . Chac can break a petrified character with her Bash attack , removing them from battle . Chac ' s ultimate attack , Heaven ' s Cataract , is used at any whim and does large damage to multiple characters , and can break them if they are petrified . As with all Basilisks , Chac does not use Heaven ' s Cataract in Oversoul form , and many consider Chac to be easier in Oversoul . The Oversoul attack pattern includes four additional attack types : Destroy Soft and Destroy Remedy , that also do damage , and are used unless an Alchemist is in the party ; Bash replaces them . She can use MP Break to drain all of a character ' s MP , and on characters at half health or below , an attack that does no damage , Hunter ' s Gaze , is sometimes used . The net effect is a significant reduction in overall damage and even risk of KO . Strategy . It is good to pack extra Softs and Remedies to cure petrified characters before Chac breaks them . In the International and " HD Remaster " versions , the easiest way to deal with Chac is to drain her MP . If she has no MP , she cannot use her dangerous Heaven ' s Cataract move , and is thus helpless against a team of Berserkers with Evade & Counter . Draining her MP can be done in various ways , the easiest of which is by using a Soul Spring . Heaven ' s Cataract will not cost MP in the original version , and this strategy will therefore fail . In the original version , an uncomplicated and effective way to defeat Chac involves bringing a Gunner in HP Critical condition that is wearing the Cat Nip accessory . Using her Trigger Happy ability will result in 9 , 999 damage per hit . Against an Oversouled Chac , the third - HP character will not be hit by Heaven ' s Cataract , and roughly 14 % of the attacks will be replaced by the harmless Hunter ' s Gaze . Killing lesser Basilisks ( Gucumatz or Kukulcan ) and then escaping from battle as soon as an Oversouled one is encountered , can guarantee a Chac in a subsequent encounter will also be Oversouled . Equipping the Adamantite accessory to either a character wearing the Berserker or the Dark Knight dressphere can help survive the powerful attacks Chac uses ; a downside is that the attack rate will be lower than usual . Another strategy is to use three hasted Warriors using Delay Buster ( again , only works on an Oversouled Chac ) , denying her from ever getting a turn . Chaining attacks on Chac also delays her turn ; three fast Thieves , especially hasted ( with Speed Bracers ) , can defeat her without her getting a chance to attack as Thieves attack twice per Attack command , and if they attack one after another they build a continuous chain . This strategy can be used to unlock the trophy Full Chain in the " HD Remaster " version . The player can set ATB mode to Active , ATB speed to fast , and have First Strike either from Thief ' s auto - ability , or the Highroad Winds / Mounted Assault Garment Grid s . Yuna and Rikku can equip Strength boosting accessories . For a specific strategy Yuna and Rikku can forgo Haste - giving accessories , while Paine equips Bloodlust and Wring , then replace Paine ' s accessories with Cat Nip and Haste Bangle / Speed Bracer . In the battle the player can try to time Yuna ' s and Rikku ' s normal attacks with Paine ' s to create a chain , with Paine as main damage dealer for her fast attack animation with Haste providing least time loss while maintaining chain ; Yuna ' s and Rikku ' s longer normal attack animations at normal speed keep Chac in stagger longer . An easy way to defeat a normal and an Oversoul versions of Chac is to bribe her with 1 , 751 , 400 gil in normal form , and 1 , 838 , 972 if she ' s in Oversoul , through the use of Lady Luck dressphere , or use the alternative way of bribing by using Slots without spending gil . As Chac never uses Stony Glare if only one character is present , one can consider fighting Chac with a single character . Chac ' s non - Oversoul version ' s physical attacks can be dodged with the Berserker dressphere ' s Evade and Counter ability , making her Heaven ' s Cataract , which she uses at any whim , the sole move a single Berserker will have to fear . Creature Creator . Fiend Tale . In the Fiend Tale endings , another notable Chac was created from the spirit of a sailor ' s son who was among many who were killed by Sin , his village destroyed . Regardless , Chac ends up gaining a new family in fiends and teaching his adopted son what he learned from his father .