Here is the full list of all 32 Spells & Secrets achievements.
Arrive at the Academy of Greifenstein.
Complete the first story act.
Defeat the Prince for the first time.
Complete the second story act.
Discover the second warding spell.
Discover the final warding spell.
Defeat the Prince while the Perfected Ward is active.
Complete the third and final story act.
Earn every other Essential Character Progress Award.
Earn every other Essential Hub Exploration Award.
Earn every other Essential Castle Exploration Award.
Earn every other Essential Student Faction Award.
Earn every other Major Award.
Defeat each floor boss at least once.
Rescue all schoolmates and visit each of them in the Hub.
Earn at least one platinum Pursuit Medal in each pursuit.
Unlock each piece of apparel available from pursuits.
Maximise your reputation with the Dreamdancers and unlock each of their apparel pieces.
Maximise your reputation with the Shinehunters and unlock each of their apparel pieces.
Maximise your reputation with the Greenguard and unlock each of their apparel pieces.
Maximise your reputation with the Fireblades and unlock each of their apparel pieces.
Collect every entry in your Collector's Guide.
Learn every spell.
Unlock each character upgrade from the Griffins Effigy.
Unlock each castle upgrade from Emils Emporium.
Improve each Junior Spell to its maximum tier.
Improve each First-Year Spell to its maximum tier.
Improve each Second-Year Spell to its maximum tier.
Improve each Third-Year Spell to its maximum tier.
Improve each Fourth-Year Spell to its maximum tier.
Improve each possible Faction Spell to its maximum tier.
Improve each Forbidden Spell to its maximum tier.