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