Extremely late in the game, you can encounter Hades, an optional Boss. If you fight and defeat Hades, you can synthesize the best items in the game. In Memoria, you will enter a room in which Quina thinks that there is water and tries to swim. After the scene, search the hidden area amongst the coral on the right side of the screen. When an ominous voice begins to ward you off, persist in the conversation to fight Hades. You must continuously press the confirm button here, since a "!" icon will not appear.

This Boss is not easy. Your crew must be in tip-top shape, and have all the right abilities and weapons equipped to survive. However, if you can outlast the master blacksmith, he will allow you to forge extremely rare and extremely expensive items.

One of them is the Save the Queen sword wielded by Beatrix. Also, you can forge the Robe of Lords, the Tin Armor, and the Pumice for the first time. Pumice lets Dagger summon the amazing Ark. You need the Hammer to forge more than one item on the list, so you must complete the Stellazzio side quest in order to get it.

Hades

Level: 92

Hp: 55535

Ex: 9999

AP: 30

Gil:9638

Weak: Holy

Steal:Robe of Lords, Battle Boots, Running Shoes, Reflect Ring

The only way to defeat Hades is to prepare extremely well beforehand. He's just a bit more difficult than the final Boss, but equipping the right weapons and abilities beforehand will take you a long way.

The best party for this fight is Zidane, Dagger, Steiner, and Vivi. Everyone needs to be at a high level, with plenty of stones to equip abilities. Equip everyone with the following abilities: Auto-Regen, Antibody, Clear Headed, and Body-Temp.
Hades performs a Curse spell on everyone, which imposes several statuses at once (Darkness, Confusion, Poison, Slow, and Mini), which can be devastating. Equipping Zidane and Steiner with the Auto-Haste and High Tide abilities also proves strategic. Vivi and Dagger should have the Half-MP ability, and you should equip Dagger with Boost. Also, make sure that Vivi has learned the ReflectX2 ability. Vivi should be able to cast Flare, and Dagger should have the ability to cast Reflect. Equip Zidane with the Ultima Weapon and the Mug and Bandit abilities, and preferably Master Thief as well, and ensure that Steiner has the Ragnarok. You can get this by completing the "Chocobo Hot and Cold" side quest prior to engaging Hades, which lets you obtain it from the Outer Island.

You have several rounds to attack before Hades gets serious. Steiner will inflict 9,999 HP of damage each round with Shock, and Zidane should steal, attack, and steal as described so many times before. He should cause around 2,000 HP when mugging Hades.

During the first turn, have Dagger cast Reflect on herself and have Vivi cast Focus. Better yet, you should consider equipping the Auto-Reflect ability on Dagger for a consistent effect throughout the battle. In the next round and each round thereafter, Vivi should cast Flare on Dagger, which will be reflected at Hades, inflicting 9999 HP due to the doubling Reflect ability. Dagger's summons will cause some amount of damage, but she is better utilized by healing the party. If a character gets KOed, cast Life on them and let Auto-Regen do the healing.

Try to dispose of Hades in under eight rounds. Otherwise, he will charge up his sword and perform Doomsday. This awesome spell levels everyone who isn't equipped with armor that protects against Shadow. Another good tactic is to fight a bunch of random battles in Memoria before this fight, and get everyone close to Trancing before taking on Hades. That way, Zidane should be able to cause a lot of HP damage to Hades with a few Grand Lethal Dyne attacks. Another good strategy is to replace Dagger with Eiko or Quina to counter Hades' Curse spell. Quina can use the Angel's Snack and Mighty Guard abilities, and Eiko has the Mini spell to counter the Mini effect caused by the Curse spell.

You receive 16,383 EXP for defeating Hades, as well as 9,638 Gil. He tells you to bring two Pumice Pieces for him to forge into the Pumice, which lets Dagger summon the Ark. You can find them by digging up a treasure on the World Map with your chocobo and after defeating Ark in Oeilvert. Summoning the Ark makes defeating Necron at the end of the game much easier.