Here is the full list of all 21 Black River achievements.
Use him to open the gate.
Thorne is here!
Meet the Crawler.
Be the meal of their party.
Just stare at it.
Get caught by Bobby.
Open the Treasure Chest while being chased by Bobby.
Get Ira and Bardra to work together.
Find Leah at the Mansion.
Meet the Deformity.
Defeat Blondie.
Witness Calisto breaking the last seal.
Summon Hallvorn.
Release Thorne from his enslavement.
Exit the village alive.
Collect all of Ivy's diary pages.
Rescue all survivors at the Bone Pit.
Get ambushed by the Deformity.
Kick his ass.
Save the villager from the zombies.
Save Matthias from the zombies.