Here is the full list of all 18 Plague of Yamorn achievements.
Complete the Prologue
Craft an item
Use a mutagen
Defeat Monsignor Kestron
Vanquish the greatest threat to the city of Yamorn
Defeat Cranium Congregation
Use the bell
Destroy the fungus
Translocate using the ancients finger
Get all skills
Collect every ring
Collect every mask
Collect every weapon
Get 100% completion
Defeat Wine Swine
Defeat Plagued Doctor
Defeat Heart of the Ancient
Destroy the BCC Extractor