Here is the full list of all 28 MAGICALSPIRAL achievements.
Find the gold chest in Sobel's Stage 2.
Collect every chest.
Get up to a 50-hit combo.
Get up to a 30-hit combo.
Beat any route within 30 minutes.
Find the gold chest in Sobel's Stage 3.
Win the fight against Medianne.
Win the fight against Salamander.
Kill every monster.
Find the gold chest in Sobel's Stage 4.
Don't open a single chest.
Avoid all the rocks in Collapsing Cave.
Don't kill any non-boss monsters.
Find the gold chest in Sobel's Stage 1.
Win the fight against Sobel.
Win the fight against Undine.
Defeat a number of monsters in Going For A Swim.
Win the fight against Sylph.
Win the fight against Haokah.
Avoid all the lightning in Thunder and Lightning.
Win the fight against Flower Golem.
Don't use any items.
Never retry from a game over.
Kill 50% of all monsters.
Get up to a 10-hit combo.
Find the gold chest in Sobel's Stage 5.
Defeat the Selector as Medianne.
Defeat the Selector as Sobel.