Time Magic
Time magic is always useful, and it's used by none other then Time Mages. Of course anyone who can get their hands on some time magic materia or an esper that can teach you some good time magic can use it too. Control the elements of time and space at the cost of only MP! Most time magic is helpful status magic, but it can also be attack magic. Here are some descriptions on many time magic spells.
Haste-Speed a character up so they get a turn to attack faster.
Slow-Slow an enemy down so they can't attack as fast.
Warp-Warp out of battle or even a dungeon.
Return-Return to the start of a battle
Demi-Gravity attack that cuts someone's HP in half.
Quartr-Gravity attack that cuts someone's HP down to 1/4 of their max HP.
Old-Make someone old and weak.
Mute-Prevent an enemy from casting magic.
Float-Allows the party to hover above the battle field and in certain places in dungeons. Be sure to cast it on everyone!
Coment-Blast an enemy with fire balls from space.
Meteo/Meteor-Blast ALL enemies with very powerful fire balls from space.
X-zone-Send your enemies to the dreaded X-zone from which they can never return.
Vanish-Makes someone invisible and protected from phyical attacks.
Quick-Allow someone to attack twice in a row.