Here is the full list of all 55 Ancient Dungeon achievements.
Destroy a Sacrifice Statue.
Damage The Beast with the Mercenary's Armament.
Carry more than twenty keys during a single delve.
Damage The Beast for the first time.
Traverse The Overgrown Gatehouse without taking any damage.
Traverse The Luminous Mines without taking any damage.
Escape The Ancient Dungeon after re-entering once.
Acquire three highly powerful items during a single delve.
Use a Bandit Box at least twenty times during a single delve.
Use The Blacksmith's Anvil to augment a weapon.
Destroy one thousand pots.
Open 250 chests
Strike enemies with a ranged weapon twenty-five times in a row without missing.
Challenge and destroy a boss with only a half-heart of health
Explore two hundred fifty rooms within The Ancient Dungeon.
Throw a dragonfruit into a pit.
Discover a secret room in the ceiling.
Traverse The Infested Dungeon without taking any damage.
Acquire four items from shops during a single delve.
Discover a secret room in the wall.
Acquire more than five full hearts of health.
Defeat a Chest Mimic.
Defeat a Possessed Armor.
Overcome a Challenge Chest's trial.
Deal at least twenty-five damage with a single strike.
Enter The Ancient Dungeon for the first time.
Damage The Beast with the Assassin's Armament.
Defeat one hundred aberrant enemies.
Raise your merchant discount to 60%.
Discover (almost) all items.
Defeat a Mad Merchant.
Carry more than two hundred fifty coins during a single delve.
Escape The Ancient Dungeon without consuming any food items.
Use a Contracting Orb to shrink yourself.
Win big on The Merchant's slot machine.
Eat every type of food item during a single delve.
Defeat a Golden Slime.
Escape the dungeon without obtaining any upgrade items.
Defeat a boss enemy with a single strike.
Traverse The Forgotten Library without taking any damage.
Escape The Ancient Dungeon after re-entering three times.
Escape The Ancient Dungeon after re-entering twice.
Lower your merchant discount to -100%.
Damage The Beast with the Mercenary's Armament in hard mode.
Damage The Beast with the Assassin's Armament in Hard Mode
Escape the Ancient Dungeon without entering a shop.
Escape the Ancient Dungeon in under twenty minutes.
Fully augment the Assassin's Armament.
Fully augment the Mercenary's Armament.
Traverse The Beast's Cradle without taking any damage.
Consume a food item made of gold.
Complete the delve of every Sealed Soul.
Complete 3 unique sealed soul delves
Escape The Ancient Dungeon with a difficulty modifier of 2.25
Escape The Ancient Dungeon with a difficulty modifier of 3.00