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