Here is the full list of all 29 Märchen Forest achievements.
Acquire all achievements.
Watched the opening event.
Brew an Antidote.
Brew a Dream Potion.
Brew the Arcane Potion, Coldwind Bloom.
Entered a dungeon for the first time.
Complete the First Layer.
Defeated the alien.
Complete the Second Layer.
Complete the Third Layer.
Complete the Fourth Layer.
Obtained Yggdrasill.
Conquer the Fifth Layer.
Conquer the Sixth Layer.
Obtained the Book of the Sea of Stars.
Activated all of the Basins of Fate.
Open the door to the Reference Room.
Obtained Dotanuki Blade.
Completed Relics catalogue.
Enroll in the Training Hall.
Win 100 battles.
Win 1000 battles.
Listen to all of Lethe's performances.
Defeat Subject (Level 99).
Defeat a Mimic.
Successfully parry 100 times.
Complete the Pirate event.
Successfully parry 500 times.
Fully complete the Extra Dungeon.