Final Fantasy X/Inside Sin

If you're either not interested in, or have already done, most of the sidequests that Final Fantasy 10 has to offer, then this will be the final stop for you. If you've not done most of the smaller sidequests, before you make any progress through Sin you should go and do them; the fiends inside Sin are quite difficult in their own right and the bosses are even harder. However, it is a good idea that if you are intending to get a full experience out of this game and challenge the likes of the Monster Arena and the Dark Aeons, then take the liberty of completing this game before you get too powerful; otherwise the bosses become far too easy and it makes the ending seem a little anticlimatic.

To Sin's Nucleus
First of all, you've got a sort of endless sea to navigate. You'll be on a watery pathway surrounded by various glyphs and symbols as you make your way northwards towards the arrow. Make sure to explore this place fully; the experience from the monsters will help tremendously (they all have a high AP yield) and there are a lot of good items to get. There is a Phantom Ring and Special Sphere on the left-hand side, and a Wizard Lance and a Level 3 Key Sphere on the right. There are several new monsters here:


 * Behemoth Kings have 67,500 HP and are basically a tougher, stronger, and more dangerous version of the Behemoths of Mt. Gagazet or Zanarkand. Power and Magic Break it (this halves the damage dealt by Heave and Flare), but be wary. If you kill it by normal means, it's last gasp move is Meteor which hits the entire party for 6000 damage; you won't be able to survive this. So, whack out your Capture weapons and make sure you land the final blow with one. Not only do you get the capture, but you avoid a painful, fiery death. Watch out as well; they will cast Mighty Guard once they get low on HP. Kimahri can learn it off them with Lancet, otherwise just Dispel it and carry on the assault.
 * Geminis come in two types; both have 36,000 HP, and both are armoured, but one has a club and absorbs ice and water elements, whereas the other has a sword and absorbs fire and thunder. Armour Break and Triple Foul work very well indeed on them, and just pound away at them until they die. Remember they both count as unique fiends if you're trying to capture them, and you need one of each to complete the area (or 10 if you plan on unlocking Ironclad at the arena).
 * Adamantoises have 54,400 HP and absorb fire. They're armoured, so use Armour Break, otherwise just wear them down; they're quite slow and vulnerable after getting rid of their armour. The only problem is their Breath and Earthquake attacks which does about 1500 fire damage/physical damage to everyone respectively; nullify this with NulBlaze or appropriate armour auto-abilities, or Protect/Shell. Adamantoises also have practically no resistance to anything caused by Triple Foul, so use that to render it completely harmless. However, it is immune to Demi, but not Bio so if you feel like letting it die in its sleep by poison, go ahead.

Note that if you've got Yuna's Nirvana by now (which is entirely possible even with only a little amount of time spent doing sidequests) and all her Aeons she will easily be the most powerful attacker, with her Holy costing 1MP and inflicting anything up to aroundabout 20000 damage.

Also, you may be wondering where to take your characters after they've finished their Sphere Grid sections:


 * Yuna should move onto Rikku's section and follow it back to the start, then into the area where Kimahri started and begin unlocking her way to Ultima (this allows you to ruthlessly exploit One MP Cost on her weapon and abuse her very high Magic stat much earlier than you could with Lulu).
 * Lulu probably hasn't finished her Sphere Grid section yet, but if she has, move her along Wakka's section to learn Drain and Osmose. If Yuna learns Ultima, use a Black Magic Sphere to teach Lulu it, too.
 * Rikku should move along Lulu's section of the grid (starting with the -ara elemental spells).
 * Wakka should move onto Auron's section and work his way back to the start (Power Break); this will bolster his Strength tremendously.
 * Tidus should move along Auron's section too; the copious amounts of Strength +4s will give Tidus a license to inflict 9999 damage (until he can break the damage limit).
 * Auron should move along Tidus' to Quick Hit; this is necessary to bolster Auron's pretty pathetic Agility and Accuracy stats.
 * Kimahri is Kimahri. He should be non-one-hittable. Otherwise, level him up...or don't use him.

Keep heading north and you'll find a save sphere at the base of some stone steps. Save, then equip all of your best elemental resistance armours and head up them. That's right folks, he's survived death three times and now he's back deadlier than ever. Say hello to...

Boss Battle: Seymour Omnis
Seymour's a little more powerful than before. Just a little bit. And he's gone a little crazy.

He's got 80,000 HP, firstly. This is a lot, but thankfully you've still got the one-turn grace of an Aeon with which to use an overdrive if you have one ready. Seymour's defences are pretty high so don't expect them to do that much damage, not to mention some are capped at 9,999 a hit, you've got to take into account Seymour's current elemental resists, and the Mortiphasms won't take more health off Seymour for you.

The Mortiphasms (the large circles around Seymour with the coloured circles on them) will help you determine his current elemental power:


 * With all four of one colour (i.e. red) are pointing towards him, he absorbs that element (in this case, fire) and is weak (1.5x damage) to the opposite (in this case, ice).
 * With three of one colour and one of another, he absorbs that element (red = fire, as before) but is NOT weak the opposing element and halves damage from the other element.
 * With two of one colour, he nulls damage from it.
 * With one of a colour, he halves that damage.

This is the same with all the other elements. However, he will also, with each attack, cast four Firagas at your party; this hindsight is necessary for giving Yuna long enough to add the appropriate Nul spell to counter his pretty vicious magical attacks. Seymour doesn't quit there, either; he's got Flare and Ultima to back them up (Ultima does about 5,000 to everyone - ouch) and, to top it off, Dispel (to eliminate your protection). The elemental resistance armours like the Phantom Bangle, Phantom Ring and Victorious are absolutely crucial in granting your party protection from his elemental attacks when the Nul spells can't save you (he tends to counter with his other spells a lot, but mainly Flare and Dispel). Thankfully, you'll get a warning when Ultima's on its way (he'll say a little speech, glow red, and Dispel your party); use an Aeon to throw Seymour's turn out of whack (he may even cast it on your Aeon, who can soak up Ultima far better than your party can).

The specifics of the Mortiphasms are as follows.


 * Seymour's normal turn, providing he's not preparing for Ultima, will always consist of four spells.
 * If there is four of one element, he'll cast four of that element's -aga spell.
 * If there is three of one element, he'll cast three of that element's -aga spell and one of the other element's -ara spell.
 * If there are two of one element, he'll cast two of that element's -ara spell.
 * If there is one of an element, he'll cast one of that element's -ara spell.
 * For example, if there were two fire, one lightning and one ice, he'll cast two Firas, a Thundara and a Blizzara. If there's three water and one fire, he'll cast three Watergas and one Fira.

As for damaging Seymour, Overdrives, Aeons (note: you can summon Anima for an interesting retort; remember who Anima actually is?), and not forgetting Holy, are all excellent ways. He's immune to pretty much every status effect like Slow, Delay, Silence, Darkness, Sleep and Power, Magic and Armour Break. Seymour has, unfortunately, finally fixed his random weakness to Poison but he isn't immune to Mental Break.

The City of the Dead
Once you've beaten him, Yuna will send him, and you'll get the after-battle screen, then progress into a new area of Sin. There are quite a few new enemies to contend with now, as well as returning ones from the Sea of Sorrow section:


 * Wraiths have exactly 22,222 HP (?) and their first turn is always Doom. They have a variety of other spells like -aga spells and Death, so watch out. They're resilient to physical attack but don't forget the Holy treatment. They are weak to Holy, but do not take their magical resistances as shown by Sensor the first time to be certain; every Wraith has different resistances.
 * Demonoliths are enemies in the same level of sheer annoyance as the Great Malboro. They have 45,000 HP, they halve all normal elements, and are armoured. They have a grand total of three attacks; one is a claw attack which hits for about 2000 damage to one person but can inflict Zombie, another is Pharoah's Curse which it will counterattack pretty much EVERYTHING with, and it inflicts Poison, Curse, Darkness and Silence. But worst of all is Breath. Unlike the relatively tame one from the Adamantoise, this one petrifies your entire party. If no-one's immune or has any resistance to petrification there is about a 95% chance you will instantly get Game Over. Your best bet is Doublecasted Demi or Flare, one person takes a Pharoah's Curse to inflict Armour Break, or a Holy. If you're trying to capture one...good luck.
 * Great Malboros are pretty much exactly akin to the Malboro of the Calm Lands but instead it's got nearly two and a half times as much health (64,000 HP, yes, only 16,000 less than Seymour) and always uses Bad Breath on an ambush, otherwise a 1/3 chance on every turn it gets. Thankfully the Great Malboro is still incredibly slow which although cannot be manipulated with either Delay or Slow you can use Hastega on fast characters and use the likes of Quick Hit; even with the amount of health it has, repeatedly pummeling it with physical attacks quickly builds up damage.

In the first area of the City, stick around by the glyph on the right until you've killed a total of 30 fiends; then it'll open for you, revealing a chest containing a Level 4 Key Sphere.