Magic in this world is controlled by Mana Seeds and Mana Spirits. The Ability to cast spells is granted by the Mana Seeds. The spells themselves must be granted by the Mana Spirits. As such Spellcasting is: the player summoning the Mana Spirit, the Mana Spirit casts the magic before unsummoning themselves. This all happens in a single Spellcasting Action for the player.
Mana Spirits do not join the party, but they do give the party access to their spells. Once a Mana Spirit befriends you, each Mana Spirit will grant access to their associated spells:
@Undine's Spells:
Healing and Support- Cure Water, Cure Water 2, Cure Water 3, Ice Saber, Remedy
Offensive- Acid Storm 1, Acid Storm 2, Acid Storm 3, Freeze 1, Freeze 2, Freeze 3, Energy Absorb
@Gnome 's Spells:
Defensive and Support- Defender, Stone Saber, Speed Up
Offensive- Earth Slide, Gem Missile 1, Gem Missile 2, Gem Missile 3, Slow Down
@Sylphid 's Spells:
Support Spells- Analyzer, Sylphid's Confusion, Thunder Saber
Offensive Spells- Air Blast 1, Air Blast 2, Air Blast 3, Thunderbolt, Thundercrash
@Salamando 's Spells:
Support Spells- Flame Saber, Fire bouquet, Blaze Wall
Offensive Spells- Exploder, Fireball 1, Fireball 2, Lava Wave
@Shade 's Spells:
Offensive Spells- Dark Force, Evil Gate
@Lumina 's Spells:
Support Spells- Lucid Barrier, Lucient Beam
@Luna 's Spells:
Support Spells- Lunar Boost, Moon Energy
Offensive Spells- Lunar Magic, Change Form, Magic Absorb
@Dryad 's Magic:
Support Spells- Revivifier, Wall
Offensive Spells- Sleep Flower, Explode
@Dryad 's Spells available only after @Thanatos is defeated:
Offensive Spell- Mana Sword Atk
Defensive Spell- Mana Sword Mag