Here is the full list of all 21 Crypt of the Serpent King achievements.
Level 7 Completed on Easy
Level 6 Completed on Easy
Level 5 Completed on Easy
Level 4 Completed on Easy
Level 3 Completed on Easy
Level 2 Completed on Easy
Level 1 Completed on Easy
Level 7 Completed on Hard
Level 6 Completed on Hard
Level 5 Completed on Hard
Level 4 Completed on Hard
Level 3 Completed on Hard
Level 2 Completed on Hard
Level 1 Completed on Hard
Level 7 Completed on Normal
Level 6 Completed on Normal
Level 5 Completed on Normal
Level 4 Completed on Normal
Level 3 Completed on Normal
Level 2 Completed on Normal
Level 1 Completed on Normal