~  Final Fantasy VI  ~ 
Phantom Beasts come from another strange world. When they die they leave behind their essence, in a magical stone. Using these stones anyone can summon them and learn new abilities. When Shiva is near her death after having been drained of life at the Vector factory, both she and Ifrit battle your party thinking they are enemies.

During the battle, they sense that the party has Ramuh's stone (an old friend). They end the fight and follow Ramuh's lead by entrusting the party with themselves as well. By sacrificing themselves, they allow the party to recieve their stones.

In this game Shiva's design goes back to having blue skin, she still has purple cloth too but now has green hair in the same style as in FF5. Oddly, her ingame sprite is like a fairy.

Boss Battle
Level: 21
HP: 3000
MP: 500
EXP: 0
GP: 0
WEAK: Fire
   Strength: 15
Defense: 200
Evade: 0%
Magic Strength: 7
Magic Defense: 110
Magic Evade: 0%
It takes some concentration during the fight and it requires the right preparations if you're not leveled up enough, just remember only Shiva or Ifrit has to be defeated. In fighting Shiva I suggest having a knight equip the Flame Sabre, a magical user with the strongest Fire spells, Sabin use physical and non magic attacks (avoid Fire/Phoenix Dance since it will not hurt Ifrit), and everyone else use their best non magical special techniques. Keep in mind that normal attacks will do very little because of her Defense (see her stats above).

Shiva's only attack is Diamond Dust, a powerful Ice-Elemental attack on all enemies that can be done once per battle. It costs 27 MP to use. It does most damage on Fire-Elemental enemies. For an early summon she's really useful.

With Shiva equipped, a party member can learn various spells as well as be able to summon her in battle. Her most useful spells in my opinion are Raspira and Aspira. However she has no level bonuses like most summons aquired later.
Blizzard 5 x10 Cold-Elemental damage
Blizzara 21 x5 Cold-Elemental damage
Raspira 12 x4 MP damage
Aspira 1 x4 drain target's MP
Cure 5 x3 restore a little HP

Esper is really known as Maboroshi Kedamono (Phantom/Dream/Illusion Beast) and Magicite was Maishi (Magic Stone, similar). No idea why these changes were made, especially Esper. Some people also call Maboroshi Kedamono, "Genjuu" but that term was only used in FF3 for the low-level Summoners (Genjuutsushi - magicians/conjurers) and has a very different meaning.

As you know Gem Dust is really Diamond Dust. Also, some spells had their original names changed from the Japanese game most likely due to space constraints. Ice was Blizzard, Ice 2 was Blizzara, Rasp was Raspil (aka Raspira), Osmose was Aspil (aka Aspira).