Here is the full list of all 18 A Timely Intervention achievements.
All Along the Watchtower
12+ Sidequest Completed
Artifact Defeated
Secret Passage Found
All Stonebarrow Lake Foes Killed
Ancient Crypt Found
Borehole Worm Defeated
Argmahn Defeated
Underworld Demon Defeated
5000+ gold
6+ Sidequests Completed
Troll Defeated
Frost Dragon Defeated
1000+ gold
Orc Leader Defeated
Hydra Defeated
A Timely Intervention
25+ Secret Rooms Found