Here is the full list of all 16 The King's Heroes achievements.
Finish with Knight
Finish with Commander
Finish with Witch
Finish with Priestess
Finish with Monk
Finish with Minister
Finish with Rogue
Finish with Archer
100+ kills Knight
100+ kills Commander
100+ kills Witch
100+ kills Priestess
100+ kills Monk
100+ kills Minister
100+ kills Rogue
100+ kills Archer