Here is the full list of all 13 Shadows: Heretic Kingdoms achievements.
Acquire the Reaper sword.
Reach level 10.
Defeat the Aphotic Spider Queen and her minions.
Successfully escape Thole.
Max out one of your skills with any puppet.
Unlock the Ishkai Sniper soul.
Earn second level
Avoid fighting the Werewolf Berserkers.
Complete Book One.
Defeat the Scorpion King.
Reach level 20.
Reach level 30.
Have Zaar fulfill his most fervent desire.