Classes, Disciples of Magic
Conjurers use spells based on nature. They wear very light clothing and fire magic from a distance, and they are typically healers. This light defense means they need to stay as ranged fighters. The Mind and Intelligence stats need the most attention here, though Piety is also important for keeping a large pool of MP.
During raids, Conjurers should devote all of their time to healing and buffing party members. This is possibly the most important role a player can have in the entire game.
Thaumaturges use destructive magic for high damage. Like Conjurers, they wear lighter armor and must keep their distance from enemies. Unlike Conjurers, they focus damaging attacks onto opponents. Players should focus on the Intelligence and Piety stats.
Thaumaturges are handy during raids, but they should keep their distance from enemies. As long range fighters, their spells are handy for keeping enemies away from any lesser-armored members of the party.
Arcanists are hybrids of a Conjurer and Thaumaturge, but even that doesn't accurately describe them. They also travel with a Carbuncle, a magical companion that assists in battle. They are also light armor wearers, so ranged combat is a necessity. Arcanists can use both supportive and destructive magic, so stats to focus on are Mind, Intelligence, and Piety.
Arcanists are very handy during raids. They can heal and buff party members, as well as hold back enemies with damaging magic.