Prester John is the name of an achievement introduced with patch 1.9 and labeled as hard in the file. The official description of the achievement requires the player to: “Own and have cores on Alexandria, Antioch and Constantinople as Coptic Ethiopia”. It is mandatory to start the game as 埃塞俄比亚, the achievement wouldn't be awarded when playing as a released vassal. The player must also follow the Coptic religion to get the achievement, though they may switch to other religions until then. The required provinces don't need to be converted to Coptic. The name of the achievement is a reference to a legendary Christian patriarch – see Prester John on Wikipedia.
Dealing with the Mamluks
Before going for the main part of achievement it may be a good idea to focus on conquering or vassalizing the Horn of Africa. Coptic nations can be vassalised easily. Feed some of them Muslim provinces and/or take the coptic idea to increase missionary strength so they are easy to convert.
The main idea is to wait for the 奥斯曼 to attack the 马穆鲁克 and attack when Mamluks are already seriously beaten. Conquer a straight line up to Alexandria and take the first province needed for the achievement. There build a ship in the Mediterranean. Send an explorer to explore into the unknown sea and find new Christian allies to help fight Ottoman. Ottoman can not take all provinces needed for Levant mission in one war and then need one war for conquer Egypt mission until its time to also attack Ethiopia. So there is time to get allies.
Dealing with the Ottomans
Nations like 波兰, 奥地利, 威尼斯, and/or whoever rivalled the Ottomans. Ethiopa can get royal marriages with them and are merely considered heretics to them. With their help, ideally when Ottomans are fighting another war, you can beat the owner of Constantinople (most likely the Ottomans) and demand the province in a peace (or two provinces, if the Ottomans got Antioch before you). After you core those provinces, you should be granted the Prester John achievement.
There is an event chain that gives you help from Portugal which makes your army into super-soldiers. Trying to go to war while this still is active is a good way to make it easier to win a war against Ottoman. Don't hesitate to go to war when Ottoman is busy in some other war, for example against QQ/Mamluks or Timurids.
A decent quick playthrough of this achievement show it can be done by around 1600 by an experienced player. But its also possible to do a more longer playthrough and get it first around 1800 if the random numbers gods are fickle.
Suggested idea groups
Ethiopia can benefit from the following idea groups:
- Exploration – Its needed to find the Europeans powers early since Europe is not visible from the start. Its also possible to colonize in the Indian ocean and conquer in India or colonize the spice islands. Another benefit of this idea is that it opens the way to central and west Africa, which the player can conquer by first colonising.
- Religious – since most of Ethiopia's enemies are Muslims, the Holy War casus belli may help getting provinces from adversaries with no diplomatic points cost.
- Humanist – with expansion mostly coming through conquest of heathen neighbours, mainly Sunni, humanist can help mitigate the penalties of religious disunity from its first idea, as well as allowing for more comfortable expansion with its flat -2 unrest and years of separatism reduction.
- Economic – especially worth it if the player has conquered or/and colonized gold producing provinces, due to the inflation reduction by the 3rd idea.
- Diplomatic - to get high diplomatic reputation and more relations so Ethiopia can ally more Europeans powers to take out Ottoman in the end fight.