Here is the full list of all 19 Symphony of War: The Nephilim Saga achievements.
Rescue all 4 children in Chapter 15.
Defeat all enemies in Chapter 12.
Complete the main story on Captain difficulty.
Army size reaches 150 Units.
Surrender all the Imperial Squads in Chapter 27.
Reach Max Faction Rank.
Unlock all Techs in a single playthrough.
Have 9 Units in one Squad.
Surrender 200 enemy Units in a single playthrough.
Use a Proof of Merit on a Unit.
Reach Faction Rank 9.
Defeat Beatrix in Chapter 11.
Class change to Tier 3.
Hire a Unique Mercenary.
Form a Bond relationship.
Find or purchase an Artifact of Legendary rarity.
Class change to Tier 2.
Reach Faction Rank 4.
Complete the main story on Warlord difficulty.