Here is the full list of all 14 Monsters Den Chronicles achievements.
Complete all in-game achievements
Play Act IV and pass wave 30 (above Beginner difficulty)
Complete a campaign with a party of two
Complete Act V
Reach level ten with ten different characters
Pass wave 10 in Act IV
Take all store categories to the maximum level
Win a battle against 3 or more enemies without taking damage
Reach level ten with any character
Complete Act III
Complete Act II
Complete Act I
Complete a campaign with the Hardcore penalty
Complete a campaign on Veteran difficulty