Here is the full list of all 20 Strawhart achievements.
Assemble the scarecrow, you say?
Deny Strawhart's offer.
Rescue the crying Critter.
Double down on Critters.
Recruit all six cultists.
Collect all apocrypha (allegedly)
Win a match of hide-and-seek.
Finally...
Witness all visions from magicks most profane.
Achieve flight through your cult.
Rebuild Archive.
Can you pet the crate?
Discover Archive's Secret.
Desecrate Astor's tomb in Valecrest.