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