Here is the full list of all 15 Heroes of Loot achievements.
Slay 5000 monsters
Drink from the well
Unlocked Barbarian character
Activate a statue
Play in the Arena room
Become level 10
Reach dungeon level 15
Get the "Lens of secret"
Kill a minotaur
Buy a titanium shield
Become invisible
Kill a cyclops
Maximise dungeon difficulty
Save a lost soul
Upgrade the difficulty of the dungeon