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