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