Here is the full list of all 35 Runespell: Overture achievements.
Finish the game
Defeat Gullveig
Defeat two Wardens stones
Deal in total more than 10 000 points of damage
Collect 10000 hacksilver in the game
Survive Wyrd Sister's Time Stop
Recruit all allies
Defeat Warghul
Defeat Dethgar and Ragnar
Win 20 battles without leaving the game
Win 15 battles in a row
Active a Powercard 50 times
Win 10 battles in a row
Win 7 battles without using any Powercards
Win 10 battles without leaving the game
Open 5 Treasure boxes
Win 5 battles without using any Powercards
Defeat Berendur twice
Deal in total more than 5000 points of damage
Collect 1000 hacksilver in the game
Deal in total more than 1000 points of damage
Active a Powercard 10 times
Use 5 card combinations in one battle
Win 5 battles in a row
Win 5 battles without leaving the game
Win 3 battles without using any Powercards
Collect 100 hacksilver in the game
Use 3 card combinations in one battle
Active a Powercard 100 times
Discover all major questlines in the game
Use 7 card combinations in one battle
Unlock all achievements
Win against an opponent with only 1 HP left on player side
Play all battles once
Obtain all powercards