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