- +10% Manpower recovery speed
- +20% Fort defense
- +20% Land force limit modifier
- +1 Land leader maneuver
- +1 Yearly prestige
- +50% Cavalry flanking ability
- −10% Stability cost modifier
- +1 Tolerance of heretics
- +1 Tolerance of heathens
- +15% National manpower modifier
- −1% Yearly army tradition decay
Cores of Ottomans and Venice make Albania desirable to conquer. You must secure alliances with Hungary and Aragon to make Byzantium more desirable. After this you can change your religion to Orthodox if you want. You will benefit from it internally but diplomacy will suffer.
In scenario where Ottomans attack Byzantium who is allied to Serbia , your first move is conquering Zeta. This should provoke Venice to attack Serbia. It is easy to white peace Serbian ally Bosnia. When you occupy Smederevo, take Zeta, Kosovo and Raska and vassalize Serbia to get into defensive war against Venice. After you and your allies occupy as many provinces as you can or you see ottoman forces near your borders, sue for peace with Istria as must have.
If they don't attack, great. But if they do, you must rapidly make spy network, take icon of St. Michael and Military commander advisor. You must fight many battles on defensive terrain, occupy Selanik and hold your capital. Sue for peace if you see that your your allies can not endure more warfare or if Skanderbeg dies.
After you take out the Ottomans, you should be concerned of Muslim Nations that would create collinations against you and you should rapidly expand into the caucuses before Russia does or else it would be difficult to obtain the Albania or Iberia achievement and need help at least 3 nations
So far you are already a great power and try not to screw up