Here is the full list of all 38 Iron Crypticle achievements.
Defeat The Phantom
Complete 10 Waves In Endless Mode
Defeat Madame Tentacles
Get Rainbow Power
Defeat A Boss Without Using A Weapon Pickup
Use 5 Different Scroll Types
Finish A Regular Room Without Using A Weapon Pickup
View 20 Item Descriptions In The Ledger
Defeat 3 Types Of Miniboss
Find The Golden Kitty
Defeat A Boss In All Its Incarnations
Collect 30 Lemons In A Single Game
Use The Atomic Fist 20 Times
Complete The First Floor On Hard Difficulty
Defeat Hexapod
Collect 1000 points worth of coins
Complete An Infestation Room
Get 100 100x8s In A Single Game
Complete The Mud Pits
Destroy A Fire Bug
Collect 1000 Food Items (Increasing Score Type)
Buy 10 Items In A Shop
Defeat Gnasher
Clear 50 Rooms Of Monsters
Collect All BONUS Letters
Use 10 Different Weapon Types
Get The Golden Poop
Defeat 1000 Monsters
Complete The Catacombs
Collect Or Buy 5 Stat Increases In A Single Game
Defeat The Giant Peepwort
Pick Up 10 Hearts In A Single-Player Game Session
Complete Castle Crushers 3 times
Defeat A Boss Without Taking Any Damage
Defeat Boulderface
Complete The Graveyard
Finish A Non-Boss, Non-Empty Room Without Taking Damage
Find A Map