Here is the full list of all 12 RAW Realms of Ancient War achievements.
Hit an enemy for 2500 HP damage
Start a cooperative game
Complete the game with any hero
Raise all of your skills to level 1
Find 5 statues of Kilthi
Complete 50 quests
Equip epic or legendary armor
Collect 50,000 gold coins
Possess 15 mobs
Kill 1000 mobs in the campaign
Complete a level without dying
Finish the game with all heroes