Here is the full list of all 40 Archvale achievements.
Defeat Maxilla.
Defeat the Fallen Pharaoh.
Defeat the Exiled Wizard.
Defeat the Grove's Blight.
Defeat the Rotted King.
Defeat the Banished Executioner.
Defeat the Sunken Queen.
Collect all Heart Containers.
Assemble the Arch Lexicon.
Obtain Avarn's Sword.
Defeat the Old King.
Reconstruct the gateway to Archvale.
Find the village of Timberwell.
Collect every badge.
Obtain the best potion recipe.
Obtain an improved healing recipe.
Defeat the Great Slime.
Defeat Frankenslime.
Defeat the Colossal Skullbot.
Defeat the Soul Serpent.
Craft 30 items.
Defeat 1000 enemies.
Perform five consecutive dashes without stamina recharging.
Enter the Twisted Caverns.
Survive the ritual of the Molten Rift.
Die.
Destroy the barrier guarding Tanglegrove.
Cash in 10 treasures.
Fully upgrade a weapon.
Complete every trial.
Complete your first trial.
Restore 10 fountains.
Complete half of your badge collection.
Own 8 hearts.
Collect all healing flasks.
Store over 10,000 gold in the bank.
Defeat the Ghost Crab.
Defeat Mongo.
Equip a shark cap and mermaid tail.
Defeat the Queen Duneworm.