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