Here is the full list of all 23 Maiden and Spell achievements.
Perfect all True Magnuses.
Clear all True Magnuses.
Clear a True Magnus
Get hit with all 6 status effects at once during Dark Magnus: Metronome.
Defeat Life Magnus: Anima in under 17 seconds.
Defeat Lightning Magnus: Phantom Voltage in under 21 seconds.
Defeat Steel Magnus: Epic Steelfall on Very Hard without taking damage.
Defeat the Collector of Stars on Very Hard.
Defeat the Heroes United on Very Hard.
Complete the Hero of Frost's Adventure on Very Hard.
Defeat Light Magnus: Lay On Hands on Very Hard without taking damage.
Defeat the Heroes United.
Defeat the Collector of Stars.
Complete the Sun Priestess's Adventure
Complete the Sun Priestess's Adventure on Very Hard.
Survive Fire Magnus: Dragon's Eye for 60 seconds on Very Hard.
Survive Water Magnus: A Bigger Fish for 80 seconds on Very Hard.
Complete the Silent Redhood's Adventure.
Complete the Silent Redhood's Adventure on Very Hard.
Follow instructions as the Silent Redhood.
Complete the Royal Arcanist's Adventure.
Complete the Royal Arcanist's Adventure on Very Hard.
Complete the Hero of Frost's Adventure.