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