Schizo

Schizo is a boss fought in Final Fantasy VII, atop Gaea's Cliff. The left head uses powerful Ice attacks, while the right head uses powerful Fire attacks. Together the boss can inflict a stronger Double Breath attack. It also counter-attacks with Tremor, which hits the entire party and is the same as Quake2 spell.

Both heads must be destroyed to kill Schizo. When each head dies, it unleashes a powerful Lightning-elemental group attack upon the party. A glitch which prevents the player from escaping random encounters occurs in the area Schizo is defeated until the player exits the area.

Strategy
The best way to deal with this boss is to focus on one head at a time. Attacks that contain multiple elements heal both heads, such as Magic Breath and Kjata. Comet, Fire2/Fire3 (for the Ice head), Ice2/Ice3 (for the Fire head), as well as Leviathan, Bahamut and Alexander are all good.

Protecting the party against elemental attacks makes the battle considerably easier: such as equipping Fire/Ice/Bolt Ring or Elemental Armlets, and linking the Elemental Materia with an elemental Materia in a character's armor. Dragon Armlet halves damage from all elements, and they can be obtained from the Blue Dragons in the area right before the Schizo battle.

Without Lightning protection the final attack will do roughly 1,500 damage to the entire party and it is cast twice in succession if both heads are killed at once. As Schizo uses Magic Points to attack, Magic Hammer on both heads can drain their MP dry to pretty much prevent them from ever attacking, so one can focus on killing or stealing with ease.

AI Script
AI: Setup {
 * TempVar:HitsUntilCounter = 4
 * Turn off Death Handling for Schizo(Right)

} AI: Main {
 * If (Count == 0 or 1 or 2) Then
 * Choose Random Opponent
 * If (Schizo(Left) doesn't have Death Status) Then
 * Use  (LeftAlive Version) on Target
 * } Else {
 * Use  (LeftDead Version) on Target
 * }
 * Count = Count + 1
 * } Else If (Count == 3 or 4) Then {
 * Count = Count + 1
 * } Else {
 * If (Schizo(Left) doesn't have Death Status) Then
 * Choose Random Opponent
 * Use  (Right Version) on Target
 * } Else {
 * If (2nd Opponent doesn't have Death Status) Then
 * Choose 2nd Opponent
 * Use  (LeftDead Version) on Target
 * }
 * If (1st Opponent doesn't have Death Status) Then
 * Choose 1st Opponent
 * Use  (LeftDead Version) on Target
 * }
 * If (3rd Opponent doesn't have Death Status) Then
 * Choose 3rd Opponent
 * Use  (LeftDead Version) on Target
 * }
 * }
 * Count = 0
 * }
 * Choose 3rd Opponent
 * Use  (LeftDead Version) on Target
 * }
 * }
 * Count = 0
 * }

} AI: Counter - General {
 * If (TempVar:HitsUntilCounter == 0) Then
 * Choose All Opponents
 * If (Schizo(Left) doesn't have Death Status) Then
 * Use  (LeftAlive Version) on Target
 * } Else {
 * Use  (LeftDead Version) on Target
 * }
 * TempVar:HitsUntilCounter = 4
 * } Else {
 * TempVar:HitsUntilCounter = TempVar:HitsUntilCounter - 1
 * }
 * TempVar:HitsUntilCounter = TempVar:HitsUntilCounter - 1
 * }

} AI: Counter - Death {
 * If (Schizo(Left)'s CustomVar:Dead == 0) Then
 * Choose All Opponents
 * Use  (LeftAlive Version) on Target
 * Schizo(Right)'s CustomVar:Dead = 1
 * Both Schizo's IdleAnim = Right Head Dead
 * } Else {
 * Turn on Death Handling for Schizo(Left)
 * Choose All Opponents
 * Use  (LeftDead Version) on Target
 * }
 * }

} AI: Counter - PreTurn {
 * If (Schizo(Right)'s IdleAnim == Both Heads Alive) Then
 * Schizo(Right)'s HurtAnim = Flinch (Both Heads Alive)
 * } Else {
 * Schizo(Right)'s HurtAnim = Flinch (Left Head Dead)
 * }
 * If (([2170] & 0x02 == 0)
 * & (Schizo(Left) doesn't have Death Status)) Then
 * Schizo(Right)'s HurtAnim = Flinch (???)
 * }
 * Schizo(Right)'s HurtAnim = Flinch (???)
 * }

} AI: Setup {
 * TempVar:HitsUntilCounter = 5
 * Turn off Death Handling for Schizo(Left)

} AI: Main {
 * If (Count == 0 or 1 or 2) Then
 * Choose Random Opponent
 * If (Schizo(Right) doesn't have Death Status) Then
 * Use  (RightAlive Version) on Target
 * } Else {
 * Use  (RightDead Version) on Target
 * }
 * Count = Count + 1
 * } Else If (Count == 3 or 4) Then {
 * Count = Count + 1
 * } Else {
 * If (Schizo(Left) doesn't have Death Status) Then
 * Choose Random Opponent
 * Use  (Left Version) on Target
 * } Else {
 * If (2nd Opponent doesn't have Death Status) Then
 * Choose 2nd Opponent
 * Use  (RightDead Version) on Target
 * }
 * If (1st Opponent doesn't have Death Status) Then
 * Choose 1st Opponent
 * Use  (RightDead Version) on Target
 * }
 * If (3rd Opponent doesn't have Death Status) Then
 * Choose 3rd Opponent
 * Use <Left Breath> (RightDead Version) on Target
 * }
 * }
 * Count = 0
 * }
 * Choose 3rd Opponent
 * Use <Left Breath> (RightDead Version) on Target
 * }
 * }
 * Count = 0
 * }

} AI: Counter - General {
 * If (TempVar:HitsUntilCounter == 0) Then
 * Choose All Opponents
 * If (Schizo(Right) doesn't have Death Status) Then
 * Use <Tremor> (RightAlive Version) on Target
 * } Else {
 * Use <Tremor> (RightDead Version) on Target
 * }
 * TempVar:HitsUntilCounter = 5
 * } Else {
 * TempVar:HitsUntilCounter = TempVar:HitsUntilCounter - 1
 * }
 * TempVar:HitsUntilCounter = TempVar:HitsUntilCounter - 1
 * }

} AI: Counter - Death {
 * If (Schizo(Right)'s CustomVar:Dead == 0) Then
 * Choose All Opponents
 * Use <Left Breath 2> (RightAlive Version) on Target
 * Schizo(Left)'s CustomVar:Dead = 1
 * Both Schizo's IdleAnim = Left Head Dead
 * } Else {
 * Turn on Death Handling for Schizo(Right)
 * Choose All Opponents
 * Use <Left Breath 2> (RightDead Version) on Target
 * }
 * }

} AI: Counter - PreTurn {
 * If (Schizo(Left)'s IdleAnim == Both Heads Alive) Then
 * Schizo(Left)'s HurtAnim = Flinch (Both Heads Alive)
 * } Else {
 * Schizo(Left)'s HurtAnim = Flinch (Right Head Dead)
 * }
 * If (([2170] & 0x02 == 0)
 * & (Schizo(Right) doesn't have Death Status)) Then
 * Schizo(Left)'s HurtAnim = Flinch (???)
 * }
 * Schizo(Left)'s HurtAnim = Flinch (???)
 * }

}

Etymology
Schizo's name may be derived from the mental disorder, which is commonly (although incorrectly) used to describe people with bipolar or dissociative identity disorder. This references the fact that Schizo has two heads, each with distinct abilities. People with bipolar disorder often alternate between periods of mania and depression, while people with dissociative identity disorder have multiple distinct personalities.

The Japanese name for Schizo is literally translated as "Twin Heads".