Here is the full list of all 23 Eternal War achievements.
Play your first match
Defeat your first enemy
Win in 10 Battles
Win in 20 Battles
Win in 50 Battles
Win in 100 Battles
Spawn a giant unit
Win 10 Battles as Human
Win 10 Battles as Orcs
Win 10 Battles as Skeletons
Win 10 Battles as Zombies
Spawn 50 Units
Spawn 500 Units
Spawn 5000 Units
Spawn 50000 Units
Win 20 Battles as Human
Win 50 Battles as Human
Win 20 Battles as Orcs
Win 50 Battles as Orcs
Win 20 Battles as Skeletons
Win 50 Battles as Skeletons
Win 20 Battles as Zombies
Win 50 Battles as Zombies