Here is the full list of all 30 Shad'O achievements.
Watch the credits till the end.
Fully explore the William’s memories map.
Pass all the special battles.
Unlock all of your companions’ upgrades in the book.
Unlock all the spells in the book.
Cast 20 spells during a battle and win it.
Cast at least once each 10 spells during a battle and win it.
Use 10 different companions during a battle and win it.
Sell 30 companions during a battle and win it.
Reach 1000 light resource in any battle.
Reach 2500 light resource in any battle.
Get 250 magic resource in any battle.
Save all the memories in nightmare mode.
Defeat the first Boss.
Defeat the second Boss.
Defeat the last Boss.
Defeat the first Boss without letting any of your companions get electrocuted.
Defeat the second Boss without using the Doc companion or the "Care" spell.
Defeat the third Boss without using the "Sacrifice" spell.
Win "The endless corridor" battle using only Collector and Greedy companions. (Spells are allowed)
Win "The slabs waterfall" battle using only Collector and Rainbow companions. (Spells are allowed)
Win the "Underneath the Christmas tree" battle using only Collector and Pulsor companions. (Spells are allowed)
Make it so that 4 Collector companions get destroyed in "The snowmen’s waltz" battle.
Win the "Dark woods" battle without using any range boost locations.
Win the "Ice trap" battle without using the Greedy companion.
Kill 1000 enemies.
Kill 2500 enemies.
Kill 5000 enemies.
Destroy 10 "Bomb" shadows before they explode.
Gulp a dozen "Shell" shadows down with your Greedy companions.