Here is the full list of all 26 Lost God achievements.
Use angelic vessels to increase abilities.
Find the hidden Grave of Yeor.
Reach the Holy Mound.
Defeat Prime Warrior.
Defeat Gant, Cursed Emperor.
Defeat Master of The Profane Order.
Defeat Last of the Legion.
Reach “The Godslayer” ending.
Reach “The Second Legion” ending.
Reach “Lost God” ending.
Complete the pilgrim’s quest.
Inherit the weapon of a rebel.
Show compassion to a friendly creature.
Learn the secret of the skulls.
Acquire every weapon.
Acquire every accessory.
Acquire every key.
Acquire every collectible.
Acquire every skull.
Acquire every angelic vessel.
Acquire a Vacant Orb.
Complete the Trail of Shadows.
Inherit the imperial crown.
Use a disguise to trick a warlock.
Catch the running chest.
Find a secret entrance.