Just a quick note here. Basically, I'm going to list each spell and give you my opinion on it, telling you if it's worth having or not. Again, this is only my opinion, as you may find something I say is worthless actually useful to you. But for those of you who want at least a viewpoint on what to take, then read on.
Note: After each Magic's Name, you'll see a number. Like, Cure 4, Fire 9, etc. This shows you how strong that spell is. Plus, next to this is a 2 digit number, like Cure 1-38 or so. Once that number reaches 100 or 00 again, the level of the spell goes up. It can reach 16-99 at the utter max, meaning it's as strong as it can be. The higher the level, the better. To increase the number, just use the spells in Battle or out of Battle if you're allowed to. For a trick to easily increase your levels, check Section XVI. Secrets for more.
Magic's Name: Barrier. Where it's found: Mysidia and randomly dropped by some Monsters. What it does: May protect you from Special Attacks and increases your Hit %. My Opinion: Eh, really up to you, as I never used it once when I had it. Take it if you want, but you don't need it, really.
Magic's Name: Basuna. Where it's found: Bafsk, Mysidia and randomly dropped by some Monsters. What it does: Removes temporary Status Ailments and it heals more and more of them as its level increases. My Opinion: Take it if you want, but I didn't bother with it and I was just fine. Esuna's more worth it anyway.
Magic's Name: Cure. Where it's found: Most of the towns in the game carry it. Not hard to find at all. Also dropped randomly by some Monsters. What it does: Heals HP. My Opinion: Probably the most important spell in the game. DEFINITELY get this and train it immediately. Very, very useful.
Magic's Name: Dispel. Where it's found: Fynn, Mysidia and dropped randomly by some Monsters. What it does: Removes the increased Status Effects on the Monsters. My Opinion: Worthless, don't even bother with it.
Magic's Name: Esuna. Where it's found: Bafsk, Mysidia and dropped randomly by some Monsters. What it does: Removes Status Ailments that continue to last even after Battle. The higher its level, the more Status Ailments it can cure. My Opinion: VERY useful. Get it as soon as you can and train it.
Magic's Name: Faze. Where it's found: Mysidia, Salamand and dropped randomly by some Monsters. What it does: Decreases the Enemy's MP. My Opinion: Worthless, just don't get it period.
Magic's Name: Fear. Where it's found: Bafsk, Mysidia and dropped randomly by some Monsters. What it does: Makes the Enemies run away. My Opinion: Useless unless you want to try and make the Enemies flee…
Magic's Name: Fog. Where it's found: Fynn, Mysidia and dropped randomly by some Monsters. What it does: Casts Amnesia on the Enemies. My Opinion: Again, worthless. Don't bother with it.
Magic's Name: Holy. Where it's found: Mysidia and dropped randomly by some Monsters. What it does: Deals Holy damage to the Enemies. My Opinion: Very useful against the Undead, as it's the only White Magic attacking spell. Definitely get it.
Magic's Name: Life. Where it's found: Mysidia, Salamand and dropped randomly by some Monsters. What it does: Revives a K.O.'d party member. My Opinion: VERY helpful. You'll definitely want this spell as soon as you can get it.
Magic's Name: Mini. Where it's found: Fynn, Mysidia and dropped randomly by some Monsters. What it does: Shrinks the Enemy and decreases their Strength and Defence. My Opinion: Again, worthless. It's not worth the time to train it and use it.
Magic's Name: Shell. Where it's found: Mysidia, Paloom, Poft and dropped randomly by some Monsters. What it does: Increases your Magic Defence. My Opinion: Eh, this is another whatever one. Get it if you want, but as for me, my guys had insanely high Magic Defence for nearly the whole game and I don't recall one Magic spell dealing over 100 damage to me, so, yeah, get this if your Magic Defence is low, but ignore it if it's above 60% or so.
Magic's Name: Shield. Where it's found: Mysidia, Paloom, Poft and dropped randomly by some Monsters. What it does: Increases your Defence. My Opinion: Again, up to you. I never used it, but if you want that little extra amount of Defence against certain Enemies/Bosses, take it, but you don't really need it.
Magic's Name: Silence. Where it's found: Bafsk, Mysidia and dropped randomly by some Monsters. What it does: Silences the Enemies. My Opinion: Again, worthless. Don't waste your time with this.
Magic's Name: Slow. Where it's found: Fynn, Mysidia and dropped randomly by some Monsters. What it does: Decreases the Enemy's Agility. My Opinion: Sigh… worthless. Don't bother with it.
Magic's Name: Swap. Where it's found: Mysidia and dropped randomly by some Monsters. What it does: Switches your HP/MP with the Enemy. My Opinion: It could be good or bad. It's good for training if you want to quickly increase your HP/MP by giving it to a Goblin or something and I guess it could be helpful if you're almost dead and Swap with an Enemy that's stronger, IF you can pull it off. Though, other than that, don't bother with it, but I'd say take it for training only.
Magic's Name: Ultima. Where it's found: Mysidian Tower. What it does: Casts non-Elemental damage. My Opinion: A VERY good spell. It's the only one in the game and it's damn powerful once it reaches the later levels. Once you get this, definitely, DEFINITELY keep it.
Magic's Name: Wall. Where it's found: Mysidia and dropped randomly by some Monsters. What it does: Deflects Black Magic. My Opinion: Again, optional. I never used it myself and with high Magic Defence, you'll be taking pitiful damage anyway, so, why even bother deflecting it? Up to you, though.
Magic's Name: Warp. Where it's found: Salamand, Mysidia and dropped randomly by some Monsters. What it does: Warps you out of Dungeons, but depending on its level, it may only warp you a floor or two. The higher level it is, the more floors you can warp out of. My Opinion: Very useful. Get it when you can, as you'll want it when you want to escape from a place fast and are weak and can't fight your way out.
Magic's Name: Aura. Where it's found: Dropped randomly by some Monsters. What it does: Increases the party's Strength. My Opinion: Up to you, once again. I never used it, didn't find much use with it, but if you want an extra edge of Strength, grab it. Otherwise, you don't need it.
Magic's Name: Banish. Where it's found: Mysidia, Salamand and dropped randomly by some Monsters. What it does: Warps the Enemy out of Battle and it can be used to warp you back 1 floor in a Dungeon. My Opinion: Worthless. It's just like Fear, really and it's not as good as Warp. Don't bother with it.
Magic's Name: Berserk. Where it's found: Jade Passage, Mysidia and dropped randomly by some Monsters. What it does: Berserks the target, increasing their Strength, but they become uncontrollable. My Opinion: Eh, up to you. I never used it, didn't have a need for it and did just fine without it. Your call, though.
Magic's Name: Blind. Where it's found: Randomly dropped randomly by some Monsters. What it does: Blinds the Enemies, lowering their Hit %. My Opinion: Worthless, don't bother with it at all.
Magic's Name: Bolt. Where it's found: Altair, Mysidia and dropped randomly by some Monsters. What it does: Causes Lightning damage to the Enemies. My Opinion: Very useful. Be sure to grab this and level it up as soon as you can.
Magic's Name: Break. Where it's found: Dropped randomly by some Monsters. What it does: Petrifies the Enemy. My Opinion: Useless. Don't bother with it.
Magic's Name: Curse. Where it's found: Dropped randomly by some Monsters. What it does: Decreases the Hit % of Physical and Magical Attacks of the Enemies. My Opinion: Again, worthless. Don't even get it.
Magic's Name: Doom. Where it's found: Jade Passage and dropped randomly by some Monsters. What it does: Causes Death to the Enemies. My Opinion: Worthless, again. It rarely works and it's just not worth the effort to level it up.
Magic's Name: Drain. Where it's found: Dropped randomly by some Monsters. What it does: Drains the HP of the Enemies and refills yours. My Opinion: It's good, although Cure's better and good luck getting it to deal massive amounts of damage. Ignore it, but grab it if you like to sap the Enemies for all they got.
Magic's Name: Fire. Where it's found: Altair, Mysidia and dropped randomly by some Monsters. What it does: Causes Fire damage to the Enemies. My Opinion: VERY useful. Definitely get this and level it up as soon as you can.
Magic's Name: Flare. Where it's found: Jade Passage and dropped randomly by some Monsters. What it does: Causes Nuclear damage to the Enemies. My Opinion: A GREAT spell. Grab it, use it, level it up and watch it do some massive damage.
Magic's Name: Haste. Where it's found: Jade Passage and dropped randomly by some Monsters. What it does: Increases the number of hits each party member has when attacking. My Opinion: It's good… when it's in the higher levels. Grab it if you want, but it'll only be useful to you when it's above 10 or so. Once it is, though, watch your guys start dishing out insane damage.
Magic's Name: Ice. Where it's found: Altair, Mysidia and dropped randomly by some Monsters. What it does: Causes Ice damage to the Enemies. My Opinion: Again, a VERY useful spell. Grab it and level it up, as it deals great damage.
Magic's Name: Muddle. Where it's found: Dropped randomly by some Monsters. What it does: Confuses the Enemies. My Opinion: Useless. Don't bother with it.
Magic's Name: Osmose. Where it's found: Mysidian Cave. What it does: Drains the MP of the Enemy. My Opinion: DEFINITELY get this. It's VERY useful when you need to refill your MP in a dungeon or somewhere.
Magic's Name: Poison. Where it's found: Dropped randomly by some Monsters. What it does: Causes Poison damage to the Enemies. My Opinion: Another good spell. Make sure to get this and level it up to cause some decent damage with it.
Magic's Name: Sleep. Where it's found: Dropped randomly by some Monsters. What it does: Puts the Enemies to Sleep. My Opinion: Again, worthless. Ignore it.
Magic's Name: Stop. Where it's found: Dropped randomly by some Monsters. What it does: Paralyses the Enemy. My Opinion: Worthless. Yet again, don't bother with it.
Magic's Name: Stun. Where it's found: Dropped randomly by some Monsters. What it does: Paralyses the Enemy. My Opinion: … This does the exact thing as Stop. Oh well, ignore it.
Magic's Name: Toad. Where it's found: Dropped randomly by some Monsters. What it does: Turns the Enemies into Toads. My Opinion: Haha, they turn into Toads… but no, it's worthless, don't waste space on this.