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