Location :: Temple of José
Ixion's high defense and high magic defense make it a good Aeon to call out when the party needs protection from an enemy's attack.

Unique Attack :: Aero Spark
Ixion shoots razor-sharp discs at a single enemy causing non-elemental damage. The attack also negates magical effects such as, Protect, Shell, Reflect, Haste, Regen, and the Nul spells.

Black Magic :: Thunder, Thundara

White Magic :: Ba-Thunder, Ba-Water

Overdrive :: Thor Hammer
Ixion unleashes a server lightning attack, hitting all enemies with lightning elemental damage.
Ixion can inflict more than 9999 HP damage once Kimahri gets his ultimate weapon Sprit Lance.

Aeon: Shiva

Location :: Acquired in Macalania Temple
The beautiful goddess of Ice. An amazing sight to the eye and an agile attacker.

Unique Attack :: Heavenly Strike
Shiva drops a giant block of ice on the enemy slightly delay it's next turn and also causes some non-elemental damage.

Black Magic :: Blizzard, Blizzara

White Magic :: Ba-Fire, Ba-Cold

Overdrive :: Diamond Dust
Shiva freezes all enemies with sheets of ice, and destroys it with a gentle snap of her finger. She really lays down the laws. Shiva can break the 9999 damage limit when Lulu acquires her ultimate weapon, The Onion Knight.

Aeon: Bahamut

Location :: Palace of St. Bevelle
Bahamut possesses the auto-ability "Break Damage Barrier." This enable Bahamut to exceed the 9999 damage limit right from the beginning. Bahamut is a mad killer, with high Strength, Defense, and Magic attributes. Bahamut's regular attack is stronger than any other Aeons. Bahamut can also cast the highest level spells. Like I said, mad killer.

Unique Attack :: Impulse
Bahamut charges up and fires up to four balls of dark magic and hurls them, damaging all enemies. Impulse is very useful when fighting multiple enemies.

Black Magic :: Fire/Fira/Firaga, Thunder/Thundara/Thundaga, Blizzard/Blizzara/Blizzaga, Water/Watara/Wataga.

White Magic :: Libra

Overdrive :: Mega Flare
Bahamut anchors itself and fires a massive breath attack the rips apart everything around it. Bahamut's Overdrive is an extreme attack the constantly deals over 9999 HP damage and will continue to grow stronger.

Aeon: Anima

Location ::  Baaj Ebon Temple
The dark Anima. First seen through Seymour. However the party can have a snatch at this one of a kind aeon through a side quest. Return to Baaj Temple from the airship, defeat geosganeo, and then enter the underwater temple. Find the six hidden items in the Cloister of Trails at each temple, and then approach each statue inside Anima's shrine. This opens the doorway to the most devastating aeon in the game, Anima!

Unique Attack :: Pain
Just look at the name, pain. The name really says it all. Anima conjures the essence of misery and anguish, and lets it all out upon a single enemy. The attack has a high chance of instant death. Pain has a long recovery time.

Status Attack :: Sleepel Attack/Silence Attack/Brain Attack, Sleepel Buster/Silence Buster/Brain Buster.

Black Magic :: Fire/Blizzard/Thunder, Fira/Blizzara/Watara/Thundara, Firaga/Blizzaga/Wataga/Thundaga, Bio/Death.

Overdrive :: Oblivion
In the most horrifying of all Aeons' Overdrives, Anima inflicts multiple non-elemental attacks on all enemies.

Aeon: Yojimbo

Location :: Cavern of the Stolen Fayth
Yojimbo is a secret aeon you can acquire by visiting the Cavern of the Stolen Fayth beneath the bridge at the northeast ends of the Calm Lands. To get Yojimbo you must fight your way through the cavern and beat Yojimbo in battle. Proceed through the cavern and speak to Yojimbo to negotiate a price for his services. He will offer his lowest initial price if you choose the option, "To defeated the most powerful of enemies." For your first bid, offer half of his asking price plus 1 Gil, so if he ask for 250,000 Gil, offer 125,001 Gil. After his next offer, raise your bid by 1 Gil. By the time he proposes 205,000 Gil, he will generally accept offers below 200,000 Gil, though not much lower. If at any point you offer him triple of his asking price he will give you 2 teleport spheres along with his services.

Unique Attacks :: Daigoro, Kozuka, Wakizashi, Zanmato
Yojimbo doesn't have selectable attacks or overdrives. As a sword-for-hire, he will attack enemies based on how much you paid him. Yojimbo's attacks will exceed the 9999 damage limit when Auron activates his ultimate weapon, Masamune.

Aeon: Magus Sisters

Location :: Ramia Temple
This trio can be yours by taking a side quest. Capture all the monsters in the Mt. Gagazet area, and return to the monster arena to get the Blossom Crown. Acquire all the other aeons, including Yojimbo and Anima, and return to Remiem Temple in the calm lands. Challenge and defeat Belgemine's versions of your aeons. When you beat her version of Bahamut she will give you the Flower Scepter. Continue to defeat Yojimbo and Anima. Then move to the door in the back and unseal it with these two key items.
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The Magus Sisters are like three separate aeons. As such, they are a bit difficult to control. There are verbal request that must be made, and weather or not they grant Yuna's wishes depends on the level of their morale.

Unique Attacks :: Camisade, Razzia, Passado
The sisters might perform their unique attacks randomly when the "Do what you will," command is selected, or they might do it when Yuna shouts, "Go, Go!" Cindy's Camisade shoots blades of fire at an enemy, while Sandy's Razzia launches her onto her target. Little Mindy's Passado will rapidly fire a burst of fifteen stingers at a single enemy.

Overdrive :: Delta Attack
When the magus sisters are all in overdrive mode at the same time, a new command, "Combine Powers!" appears. The sister will join forces and perform one of the most devastating overdrives in the game, Delta Attack.