As Tidus put: "a city dead for a thousand years…"
To the Dome
Turns out the blitzball dome is the holy place here. There's quite a bit of distance between you and it, though — a series of broken road sections leading across the water. All the battles you fight here will be with the same monsters you encountered inside Mt. Gagazet, perhaps as different combinations. The first chest along the way contains a Fortune Sphere, whilst the second contains a Spiritual Targe for Rikku. The monster encounter rate is lower than that of Mt. Gagazet though, which is a good thing.
After getting to the entrance you'll meet with some random guy who will verify that you've been to all the places you need to. You have, so you can enter the dome. There's quite a long and complicated path to a save sphere, then on again to a staircase which leads to the Zanarkand Cloister of Trials. The enemies you fight here are slightly more powerful versions of the monsters you fought when you were gatecrashing Seymour's wedding, so check the Bevelle page for the necessary information. The monks here, however, are zombified (thus allowing Yuna to become an offensive character — use Curaga on them for an overkill, or Life for instant death), and you will encounter Defender Zs from time to time. These are essentially the same as the Defender X you fought except they have less HP (42,300), and will not use Slowga or Mighty Guard.
Also note that at this point you can choose to make the upcoming battles a significant amount easier by having Yuna learn Holy at the end of her Sphere Grid section. This actually gives her something to do during her turns if she doesn't have anything to heal, not to mention doing a lot of damage (but this is balanced by an MP cost of 85). However, you might complain that it's a lot of leveling up to do. If you've got Yuna to learn Curaga or possibly Regen by this point it isn't that much more at all, and at the same time you can get other people to learn abilities that will make them more useful as well. Grinding for Holy will also give you the opportunity to make sure that all of your Aeons are in Overdrive. Having them in Overdrive will make the last part of the battle against Yunalesca much easier.
Once you enter the dome, after a short distance you'll go through a tunnel of sorts with a chest on top of it. When you come out the other side you can use a ramp to the right to climb up and get the chest, which contains 10,000 Gil. Further along is a save sphere. There's a Friend Sphere along one of the forks from the part where you see Seymour and his mother from a long time ago, and further along (just before the exit) you can backtrack down a girder to reach a hidden chest containing a Lvl 3 Key Sphere (if your characters are beginning the reach the end of their sphere grid sections you will most likely be running a little low on these, so make sure you pick it up). Along the next corridor you can pick up a Luck Sphere from a chest, then carry on up to the top. Use the Save Sphere, then head down the stairs to the Cloister of Trials.
Zanarkand Cloister of Trials
The puzzles here are a little like Tetris — you've got to select the appropriate tile arrangements from the illuminating floor sections to make the symbol that appears on the screen. The main problem is that you only have shining lights to tell you where these tile arrangements are and vaguely discoloured tiles to suggest where these pieces fit on the floor. There's no distinguishing between them until you step on the shining square, but no two arrangements overlap. The picture shows the arrangements of the tiles, with the black dots showing the buttons that activate them.
So, at the bottom of the stairs, step on the green square at the front of the tile section to activate the whole thing. You'll see a series of arrangements appear on the screen — so step on the ones to match them, using the picture provided (or work it out yourself if you wish). The white squares aren't significant at the moment but they will be later on when you return here. If you step on a tile that doesn't fit into the arrangement you're trying to make, you'll have to start over from the beginning of the arrangement.
Once you've done this six pedestals will come out of slots on the wall and the door to the next area will open. In the next room, which is quite big, take the Kilika Sphere from the slot by the screen on the wall (not the Besaid Sphere, since that powers the screen) and place it in the center-left pedestal. This will cause the Kilika Glyph to appear on one of the hexagonal plates around the hole in the main room. Then, you can start solving the arrangements of tiles that match the Yevon symbols for each temple. We'll start with the top-left one, so push that pedestal in.
You need two red corners, two blue L-shapes and two green S-shapes, so locate them on the larger of the two diagrams and touch all of them (without stepping on any others). When it's complete the screen will flash yellow, the arrangement will disappear, and another glyph will appear on the hexagonal panels around the hole in the middle of the room. Return to the first room and push the lower-left pedestal in to trigger another Yevon symbol match-up. This one requires three red corners, two blue L-shapes, one green S-shape and one yellow straight piece (thankfully there's only one of these in this room, in the bottom left corner). Complete this, and another glyph will appear on a hexagonal plate.
Work your way through the other two match-up puzzles but leave the pillar with the sphere slot until the end (they're really easy when you know where each of the arrangements are). This pillar takes the Besaid Sphere that powers the screen in the other room and obviously you can't complete the puzzles without the screen. Once you've placed the Besaid Sphere in the last pedestal and activated all the glyphs, a lift will appear in the hole in the previous room. The screen in this first room will be frozen with seven white squares on it; you'll have to leave this until you return. Save, then go through into the large room to start a boss fight.
Boss: Spectral Keeper
Any boss which can magically transform a room into an endless void of glyphs shouldn't be messed with, but thankfully this guy isn't too difficult to handle if you know what you're doing. You'll be fighting this battle standing on the glyphs over the void; you can use the trigger command Move to change which glyph each character is standing on (two characters cannot occupy the same glyph). The Spectral Keeper has 52,000 HP and will counter each attack you make on it with a sweep of its claws; it does 2,700 damage to everybody it hits and extends over a range of three glyphs (one either side of the one it's facing). Since this damage quickly accumulates, you should first start by moving the character in the middle of the other two to the exact opposite glyph behind the Spectral Keeper. This ensures that its counter-attack will only ever hit a maximum of two people. It has two other attacks; Berserk Tail, which does about 1,500 to one person and inflicts Berserk (uncontrollable attacking in this complements its counter-attack; you will quickly lose your party in this case). The other is Glyph Mine, which will, quite literally, mine a glyph — the glyph number is displayed on the turn list and when it comes up, anybody standing on that glyph dies. So simple enough; Move out of the way. Summoning an aeon will cause it to use this trick; after one or two turns the glyph will kill the aeon, but that's enough time for an overdrive or at least to inflict a little extra damage upon the Spectral Keeper. Make sure to get rid of Berserk as soon as a character gets it. Remember to have Protect on everyone, as it will lower the damage severely.
It's immune to Power and Armour Break (which really sucks since its physical attack and defense are both quite high) but it does succumb to Mental Break. It is also immune to Slow and Delay (so any attempt to nullify its worryingly high speed will have to come from Haste), as well as Poison and a variety of status effects apart from Silence which does absolutely nothing against it. This battle will take a long time as you will need to keep using items and turns to deal with the situations it presents you, but providing you don't attack it that often and leave the attacking to somebody that can inflict a lot of damage per hit, you should be fine. A Grand Summon of Bahamut followed by a nice Mega Flare should be good for about 20,000 damage at this point, maybe even as high as 35,000 (if Yuna's finished her Sphere Grid section, and don't forget, you've got Holy as a last-ditch attack method).
Once the Spectral Keeper is dead the room will return to normal and the glyphs will combine to make a lift which takes you down to the hall of the Final Summoning. After the cutscene and the battle results, you'll be at the bottom of the lift; use the save sphere down here then go through the door. Unfortunately, the original fayth of the Final Aeon has lost all of its power, and it cannot be used to summon the Aeon. But it seems Lady Yunalesca has a solution; so go through the portal to meet her.
Turns out it's not as simple as the summoner fighting Sin. After the long scene you'll confront Lady Yunalesca over the matter of defeating Sin, and you'll uncover more of the lies surrounding Yevon. After a small motivational speech from Auron and the rest of the party, you'll fight Yunalesca!
Boss Battle: Yunalesca
The First Form
Yunalesca is 1,000 years dead but she is certainly pretty good at…liberating people. Fighting her is divided into three distinct forms; each one is a little harder than the one before and has more HP. In this case, Yunalesca has 24,000 HP in her first form, 48,000 in her second and 60,000 in her third.
Yunalesca's first form isn't particularly dangerous but she'll counter anything you use against her; Blind will be used against anyone who physically attacks, Silence against anybody who uses magic on her, and Sleep on any overdrives used. This quickly accumulates and you will have to make sure you try and cure all of the status effects you get as the battle becomes very difficult very fast once you get to the second and third forms. Yuna's Holy will probably hit for nearing 9999 damage, and Hastega from Tidus will help speed the whole process up. Yunalesca's main normal attack is to use a weak white energy blast on you; it does about 200-300 damage on whoever it hits but it dispels all positive status effects. She also has a spell called Absorb, which takes about 2,000 of a character's health and adds it to hers.
This is the form you want to make sure everybody gets a turn in with; the battle becomes a little more demanding on heavy-hitters towards the end. When you're ready to progress (don't bother to use spells like Protect or Shell as they'll only get dispelled), make sure Yuna is in the party, knock off her remaining HP and watch as she grows into her second form.
The Second Form
Now things get harder. The first move, regardless, of anybody will be Yunalesca using Hellbiter. This does a quite feeble 150-200 damage to everyone but inflicts Zombie with a perfect success rate (providing you've got nothing equipped with Zombie Ward or Zombieproof equipped — if you have, unequip it now; you'll see why soon enough). This is both good and bad news. It's bad news because this means healing actually hurts you (and Yunalesca's array of powerful healing magic now become offensive spells) and so the damage Yunalesca inflicts can't be healed without first using a Holy Water. However, this is good news because of what the first move of Yunalesca's final form is; Mega-Death, which is 100% inescapable instant death on every party member. However, Zombie immunises you against the effects of instant death. So, before you kill off this form, make sure at least one (preferably two or three) of your active party members are in zombie.
Yunalesca no longer casts an appropriate spell to nullify whatever you use to attack her but rather she'll use her white dust attack as a counter-attack to most things. As a result, positive status effect spells (including Hastega) are now pretty much useless, but Yunalesca isn't that fast and so not too difficult to deal with. Regen on a Zombie character is a lot like Poison except it does less damage but every turn regardless of whether it's that character's or not. It'll do about 150 damage a turn to a zombified character but will work in reverse if you get rid of it with a Holy Water. Cura will do about 1,500 damage to a zombie.
If you had Yuna in the party after defeating Yunalesca's second form, Yuna will be inflicted with Zombie. Cast Haste on Yuna and remove her from the party (bringing her in only to heal and cast a couple rounds of Holy from time to time). Bring Yuna back in when Yunalesca has around 9000 HP and finish her off with Holy. Since Yuna is zombiefied, she will not die when the third form of Yunalesca uses Mega-Death.
Get ready to fight the third form by letting Yunalesca use Hellbiter, then knock off the remaining health and watch Yunalesca grow once more.
The Final Form
Now it has a nice, big, ugly face. To top it off, if no characters are zombies despite this guide's considerable warnings, your campaign to end Yunalesca's 1,000 years of "liberating" and bestowing the Final Aeon upon summoners will end here as Mega-Death will kill everyone. Otherwise, you will escape instant death.
Her final form has 60,000 HP, as mentioned before, but now you will have to contend with the strongest healing magic Yunalesca has to offer (Curaga is capable of doing up to 5,000 damage to a zombie), Hellbiter to re-inflict Zombie, Mind Blast which is particularly used on Aeons which does about 500 damage to everyone (and if used on an Aeon, inflicts Curse), and Yunalesca will recast Mega-Death from time to time so make sure you have at least one zombie in your active party to survive that when it happens. Yunalesca retains her dispelling white dust counter-attack, and as before is immune to pretty much any status effect that isn't positive. Summoning Aeons is a good idea here as you can get a few good moves in dealing damage to her before she kills it off; she'll use Absorb and Osmose a lot on Aeons to try and replenish her health, but Bahamut should be able to deal out damage faster than she can replenish it, at least until he dies (and you can't use Mega Flare either since you're cursed).
Yunalesca is not too difficult providing you consider each attack and keep an eye on the turn list to make sure you've got enough turns to carry out whatever it is you're trying to do (remember, using Ethers on Zombies will rob them of MP, not replenish it — this is important if your main damage tactic is Holy).
If you want to finish the battle quickly, have Yuna (who should still have Haste on her) summon her Aeons (they all should be in Overdrive). It is likely that Valefor will end up being killed by Absorb and Osmose after his overdrive attack. Ifrit and Ixion might survive Yunalesca's combo attack but dismiss them anyway because you won't get a second overdrive from them. Shiva is likely to survive the combo attack and get a second overdrive, so use it against Yunalesca and enjoy your victory. If you don't get a second overdrive from Shiva, bring in Bahamut and use his overdrive to finish Yunalesca off.
An alternative to making sure you have at least one zombie at all times is, before entering the battle, to customize a piece of armor with both Zombieproof and Deathproof. Deathproof uses 60 Farplane Winds-this is the amount the arena master gives you for capturing every creature in the Calm Lands-and Zombieproof uses 30 Candle's of Life, which Rikku can steal from the zombie monks in the Zanarkand Ruins. Yunalesca's attacks do fairly low regular damage, relying on zombie and healing magic to inflict high damage, so if you use this on a character with fairly high HP, you don't need to worry about keeping one of your members as a zombie. When Yunalesca casts Mega-Death, Deathproof keeps this character alive. Simply use a Phoenix Down (or Life, if your character has it) to resurrect the rest of your party, and return to battle.
In the X/X-2 Remaster, Zombieproof costs 10 Candle's of Life per customization.
Leaving Zanarkand
Spira now no longer has the Final Aeon to defeat Sin and as a result there is no apparent way of killing it. Still, Tidus remains optimistic that he'll "find a way". Before you leave Yunalesca's chamber/void of sorts, make sure you descend the stairs at the edge of the platform. When you reappear on the other side of the room, the Sun Crest will appear in a chest at the top of the stairs leading down. If you missed it, you may return to Yunalesca's chamber after watching Auron's memory cutscene! Getting it early is important because, like some of the Destruction Sphere treasures of the other temples, a Dark Aeon (specifically Dark Bahamut) will be in this room the next time you return here and so failing to get the Sun Crest now will require you to come back and get it after killing Dark Bahamut; and for your characters right now that is borderline impossible.
Once you've got it, leave the room and make the trek back through the ruins (you won't have to go back through the main dome section) you'll be outside Zanarkand Ruins and Sin will show up; don't worry, you won't fight it. It'll leave and the airship will reappear after its absence. After watching Sin fly off into the sunset, you'll board the Airship once more.
Return
- Dark Bahamut
Returning for Destruction Sphere
To break this seal, first return to Zanarkand Ruins and make your way along until you reach the trials. You will notice the screen in front of you now shows 7 white 2 by 2 blocks. As with the original trials, you must find these blocks by stepping on the small lights on the floor. There are 3 of these white blocks in the first room, in the top right, mid-left and mid-center. The final 4 are found in the second room, on the mid-left (2nd from the white-blue glyph), mid-top (2nd from the blue glyph), top-right (2nd closest to the stairs) and mid-right (across from the red/pink glyph). After lighting up the 7 squares, the screen in the first room will move away revealing the destruction sphere. Take this and place it in the hole on the right of the screen in the second room to reveal the chest, which can be opened to break the (hopefully) final seal and net you a Magistral Rod to boot!
When you have broken all the seals, return to Baaj Temple and examine all 6 statues which should all now light up. When they do, the large seal will break, and you will be able to enter the Chamber of the Fayth to talk to the Fayth and then obtain the Dark Aeon, Anima.