Alright, this game isn't exactly magic-oriented, but there are still some magics that you simply can't live without,
and some others which make some dungeons a breeze.
Now the question is, which magics should you give priority to?
Let's decide!
This is my list, followed by arguments:
WHITE MAGIC:
Cure - vital for healing your chars, because they *will* lose HP a lot
Life - very, very important; how fun is it being stranded with 3 KO:d chars in the middle of a hard cave?
Heal - Poison, Dark, Curse and Dumb, enough said
Safe - ...and suddenly, 500 DMG only dealt 200 DMG...
Shell - ...and suddenly, Meteor, spell of destruction, didn't kill you...
Wall - ...extreme magic defense, WHAT!
Change - Level-building, anyone?
Exit - incredibly important for getting out of dungeons easily, saving you some tedious backtracking
Holy - extremely useful against undead monsters and whatnot
Ultima - once you actually manage to reveal its weird stat-secrets, it becomes the best spell in the game!
BLACK MAGIC:
Fire - ice monsters, enough said
Ice - fire monsters, enough said
Bolt - water monsters, enough said
Haste - increases amount of attacks, and puts Berserk to shame
Flare - extreme fire attack, couldn't go wrong