Here is the full list of all 27 Masquerada: Songs and Shadows achievements.
Defeat the Antiquarian.
Fully upgrade a skill.
Defeat the Triplets.
Defeat the Greater Bolgia.
Complete the Prologue
Defeat the Saltbreather.
Defeat the Matron.
Defeat the Ancient Feravaro.
Defeat the Chimera.
Defeat the Mangiatore.
Defeat the Ridiro Queen.
Win the duel.
Defeat the Brehon.
Clear the final battle.
Watch the Epilogue.
Collect all inks and runes.
Collect all the codices.
Respec once.
Practice in the Training Grounds.
Revisit a scene.
Listen to all of Kalden's optional dialogues.
Listen to all of Amadea's optional dialogues.
Listen to all of Tiziana's optional dialogues.
Listen to all of Vasco's optional dialogues.
Listen to all of Leventhos' optional dialogues.
Activate 100 Mask abilities.
Trigger 250 Elemental Tags.