Cúchulainn ( Final Fantasy XII boss ) Cúchulainn is an Esper boss in " Final Fantasy XII " . The party fights him in the middle of the Garamsythe Waterway , and defeating him unlocks his license on the License Board . Cúchulainn is also fought in the " International Zodiac Job System " Trial Mode at stage 42 along with four Foobar s . Finding Cúchulainn . The player must complete the Wraith and White Mousse Hunts to get the control of the sluice gates in Garamsythe Waterway . From the first central area , with the save crystal , the player should see four sluice gate switches : 3rd , 4th , 10th , and 11th area . The steps to accessing the area where the player can find Cúchulainn are as follows : Now only sluice gates No . 3 and No . 4 should be on and the player can access the middle of No . 1 Cloaca where Cúchulainn is fought . It is recommended to save the game before engaging him . Battle . Cúchulainn is accompanied by Foobars . While the Foobars respawn , killing a certain number of them will eventually cull their regeneration . The battle ' s special attribute is that health will be constantly drained from all active party members . Cúchulainn routinely casts Bio and Malaise , which may KO weaker characters . He also uses Impure that inflicts Disable and Immobilize . The battlefield is small , so even Immobilized the characters can reach a target most of the time . He also casts Invert , inverting the target ' s HP and MP . If Cúchulainn uses Invert to a character with low MP the constant HP drain will quickly finish them off as well . However , as Invert tends to replenish a character ' s MP stock it may even be useful . The main threat to the party is Disablega , fatal if it hits all members . Strategy . While standing near the save crystal in the Central Waterway Control the player should buff the party with Regen , Haste , Protect , and Shell . One may also want to set up gambits to recast Regen , Haste , and Shell as they wear off . It is also useful to Bubble the entire team . Although Bubble Belts grant Bubble , they do not fill up the characters ' HP bar the way the spell does , so if one has to unequip and reequip the Belts during battle , the characters ' HP will not be adjusted . The party ' s tanks should be buffed with Bravery and Berserk and mages with Faith . If one tries to complete this battle with a guest character like Larsa , using the gambit Ally : any > Phoenix Down / Raise may be counterproductive , as the character will likely be KO ' d early in the battle and soon after being revived . Because the battlefield ' s drain effect is faster than Sap and can kill characters , the player must consider the value of curative gambits . If all the characters constantly heal to keep their HP topped off yet still struggle , it may be worth disabling usual curative gambits to rely on Arise ― if it is available ― to free up time and attempt to end the battle quickly as Cúchulainn ' s HP is not overly high . If one wants to avoid KO , it is important to keep HP above 1 , 000 . Having Curaja is useful as a healing spell for this battle . Killing Foobars should be the priority at the beginning , either by means of Quickening Concurrences , or by directly attacking . To counter Disable and Immobilize , the appropriate anti - status accessories can be equipped when the Impure begins to cast . When Cúchulainn begins casting Disablega , one should equip Black Belts for protection if not equipped already , or cast Esuna to remove the effect . Other appearances . " Final Fantasy Record Keeper " . Cúchulainn appears on a stamp for multiplayer mode .