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