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