Here is the full list of all 43 Chronos: Before the Ashes achievements.
Complete the Game in NG+ Mode
Upgrade Any Weapon to Level 9
Solve the Flautist Riddles
Unlock Everything
Complete the Game on HEROIC
Complete the Game at age 21 or younger
Put 30 Attribute Points into Arcane
Exchange your Starting Weapon with a Krell Version
Put 30 Attribute Points into Agility
Acquire the Lightning Stone
Complete the Game on any Difficulty
Complete the Game on ADVENTURE
Defeat the Dreamer
Defeat the Labyrinth Guardian
Upgrade Any Weapon to Level +5
Acquire the Labyrinth Scythe
Return a Keepsake to the Krell King
Acquire the Shadow Stone
Defeat the Pan Guardian
Acquire the Pan Shield
Read 10 Books or Scrolls
Defeat the Red Widow
Travel to Ward 16 by Way of the Mirror
Meet the Pan Flautist
Create a Rare Dragon Shard
Put 30 Attribute Points into Vitality
Acquire the Pan Spear
Craft a Krell Mace
Put 30 Attribute Points into Strength
Defeat the Stone Golem
Acquire the Sun Stone
Defeat the Krell Guardian
Read 5 Books or Scrolls
Acquire the Krell Hidden Weapon
Acquire the Krell Shield
Open a Dragon Inscribed Box
Unlock Your First Trait
Acquire the Krell Hammer
Upgrade Any Weapon
Acquire the Fire Stone
Meet the Krell Blacksmith
Acquire a Dragon Heart