Here is the full list of all 38 Moss achievements.
Finish the first book of Moss.
Defeat the serpent Sarffog.
Destroy a Forged enemy with an aerial attack.
Destroy a Forged enemy with a controlled Scorcher.
Climb to the castle bridge alongside Quill.
Annoy Quill by delaying the adventure.
Collect a large amount of Relic Dust.
Guide Quill to destroy multiple thorn patches.
Enter the Abandoned City alongside Quill.
Enter the Namelhook Mining cave alongside Quill.
Startle Quill from behind.
Unlock the path to the Mire Temple's altar room.
Take control over many Forged enemies.
Light the torches of the Knights of the Sun.
Collect a small amount of Relic Dust.
Give Quill a high five.
Use a Screecher to unlock the path forward.
Enter the Mire Temple alongside Quill.
Defeat the Screechers first encountered in the Mire.
Use your power as a Reader to heal Quill for the first time.
Follow the Starthing and Quill into the impassable Mire.
Enter the Clearing alongside Quill.
Discover your first Forgotten Piece.
Use Quill's sword to cut down a lot of grass.
Collect all of the forgotten fragments.
Collect all of the Relic Dust.
Find a low-hanging path to the town pub.
Destroy two or more Screecher enemies with a controlled Ticker.
Rescue Argus without a single death.
Break everything within the town pub that can be broken.
Use your power as a Reader to break many objects.