Age of Empires II: Definitive Edition (PC) - Achievement - Diplomacy is for the Meek
Kill the Scythian Prince and defeat the Scythians in the first Attila the Hun mission "The Scourge of God".
Your goal in this mission is to kill two of your three enemies. The Scythians hold the most territory and can be allied with once you rescue their prince from the Eastern Roman Empire (blue), making it ideal to focus on defeating the other two enemies under normal circumstances, however for the purpose of this achievement, they must be destroyed. Although the Scythians appear to hold a lot of land, they aren't difficult to kill - This is the first Attila the Hun mission after all which was the first mission in the first expansion to Age of Empires II. This video shows where in the Easter Roman Empire camp the Scythian prince is located. He must be killed along with the Scythians for the achievement to trigger. It does not matter in which order you decide to do this. The achievement only seems to trigger upon completion of the level.