Here is the full list of all 23 Fall of Light achievements.
Kindle a bonfire
Free Aether from a jail
Kill the Guardian of the Graveyard
Die
Consacrate a Shrine of Power
Consume one sunray
Use all Shrines of Wisdom
Collect all Echoes from the Other Side
Collect all Fragments of Luce
Talk with all NPCs
Discover all secret areas
Collect all Elemental Shards
Kill the Guardian of the Water Shard
Kill the Guardian of the Electricity Shard
Kill the Guardian of the Fire Shard
Kill the King
Kill all Giants
Defeat the Guardian of the Threshold
Complete the game with the normal ending
Complete the game with the bad ending
Complete the game in Nightmare game mode
Read all books
Complete the game with the good ending