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