Here is the full list of all 17 Hell Warders achievements.
Completed Act 1 In Normal Difficulty
Attain Max Rating on all missions
Completed Act 2 in Normal Difficulty
Completed Act 3 in Normal Difficulty
Completed all acts in Normal Difficulty
Completed Act 1 in Hard Difficulty
Completed Act 2 in Hard Difficulty
Completed Act 3 in Hard Difficulty
Completed all acts in Hard Difficulty
Attain max rating on all missions of Act 1 in Normal Difficulty
Attain max rating on all missions of Act 2 in Normal Difficulty
Attain max rating on all missions of Act 3 in Normal Difficulty
Attain max rating on all missions of Act 4 in Normal Difficulty
Attain max rating on all missions of Act 1 in Hard Difficulty
Attain max rating on all missions of Act 2 in Hard Difficulty
Attain max rating on all missions of Act 3 in Hard Difficulty
Attain max rating on all missions of Act 4 in Hard Difficulty