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