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