Okay, time for some party-switching shenanigans. Exit the prison cell (using the Prison Key in the process) then when you're back in the dungeon, exit by heading up the stairs to the left. Stand in the green circle, switch to the other party, then exit the castle by heading down. Save your game if you wish, then return inside the castle as Squall and company.
In the main hall, use the green party switch circle again to switch to the secondary party, make sure they're junctioned up (or at least that they have Enc-None to avoid trouble) then go through the door beyond where you fought Sphinxaur/Sphinxara. Run on the chandelier and it'll kindly deposit you in the room below. Run right to find another green party switch circle, and more importantly, a lever on the wall. Interact with the lever to depress it (aww, cheer up buddy - you're gonna be complicit in a murder!) then switch back to your primary party when prompted.
Exchange junctions back to the main party, heal up, then go through the door beyond where Sphinxaur/Sphinxara once lurked. Cross the chandelier - now that your secondary party is below, holding the lever, it'll stay in place - and go through a door beyond to find Krysta on a balcony. Before you join battle, make sure ice magics aren't equipped to Elemental Attack, as Krysta is immune. If you have Auto-Shell, it's worth equipping. Otherwise, there's not much you can do to prepare.
|Status Resistances:||Immune to most status effects; Haste 0% -- Slow 70% -- The End 0%|
*Only if you didn't draw Carbuncle from the Iguions back during the Sorceress Assassination Mission section of the guide.
Krysta is a fairly passive boss, only using melee attacks and a Charge attack unless provoked... and any offensive action you take provokes it to counterattack. It's counterattack is moderately powerful, but it should be dangerous enough to cause serious concern, especially since you can just... you know, stop attacking and heal? Auto-Protect will reduce damage from most of Krysta's attacks, so be sure to cast it. That said, Krysta's most dangerous attack is magical.
Krysta has an absurdly high Magic stat. At around level ten (likely the lowest you'll be when you fight Krysta) it'll have a Magic stat of well over 100, and by level 30 Krysta's Magic stat will max out (255). When defeated, Krysta will unleash an Ultima spell, which can be quite painful if your HP aren't maxed and you don't have Shell or Auto-Shell, so make sure to cast it, if necessary.
Given Krysta's attack power, it's amusing that Krysta has relatively low HP, possessing around 7,000 HP at level 10 while maxing out at 16,000 HP at level 100. You might say Krysta is a... glass cannon? Surprisingly, we don't get paid for humor, that all comes free. That said, Krysta's Vitality score is rather high, start out at just over 200 and growing anemically to around 230 by level 100. The solution, of course, is Meltdown, which will allow you to do significant damage to Krysta and kill it in fewer hits, thus prompted fewer counterattacks. A single Aura-powered limit break should be sufficient to put Krysta away.
So, protect yourself with Shell, hit Krysta with Meltdown, finish off Krysta quickly, then with any luck (luck here is a synonym for high HP and Shell) you'll survive Krysta's Ultima finisher. Be sure to draw Carbuncle from Krysta if you didn't acquire this GF from the Iguions at the end of disc 1. This is your last chance to acquire this GF. When the fight is over, you'll gain the customary 30 AP as well as an Elem Guard, which you can use to teach a GF the Elem-Def-Jx4 ability.
Unseal the "Item" or "Command Ability" power, whichever you didn't get previously. Aside from the ability to revive fallen companions you should now have almost every battle power available to you, which is frankly enough to challenge Ultimecia... but why stop short when there are more monsters to kill? Your next target - Gargantua - beckons.