Here is the full list of all 30 Curse of the Dead Gods achievements.
Defeat Ratyapu, the Abomination
Write 5 Bestiary entries
Defeat Malok paal, the Flesh Monstrosity
Unlock 5 Forsaken Weapons
Defeat Litz & Nepac, the Cursed Twins
Start a "Special Event"
Defeat Xucat', the Witch
Achieve a x10 "Greed Kill" series
Defeat K'ax taca, High Lord of the Storm
Defeat Xak'olchir, the Blood Hunter
Unlock a Blessing of the Dead Gods
Complete the room of Trials
Defeat the Dark Avatar of the Jaguar
Defeat the Dark Avatar of the Eagle
Defeat the Dark Avatar of the Serpent
Defeat Clovis Pardieux, Champion of Death
Become the new Champion of Death
Complete 10 different "Special Events"
Unlock 20 Blessings of the Dead Gods
Unlock 20 Forsaken Weapons
Write all Bestiary entries with their complete sketches
Unlock all Weapon Altars upgrades
Get 3 successful Parries in less than 2 seconds
Lift the Final Curse
Equip a hidden Champion weapon
Make 10 Blood Offerings during a single exploration
Complete any exploration with 50 or more Constitution
Complete any exploration with 50 or more Dexterity
Complete any exploration with 50 or more Perception
Equip the three weapons slots with Cursed weapons