Here is the full list of all 15 Witch Combat achievements.
Die 20 times
Destroy 10 ravens
Defeat 10 of the witch
Destroy 10 flying skulls
Die from the blade
Collect 50 coins
Get more than 6666 points
Complete five levels
Complete 10 levels
Complete 15 levels
End the game
Get a Super Lightning
Get a Super Speed
Get a Shock Wave
Destroy 20 training bags