We have Al-Rahim, of course, but Vlad speaks of the Ottomans and his idea of waging war upon them for revenge. Sixtus exposes the same idea to his imprisonned brother at the end of E08S01.
Sixtus also prophetizes the theft of Leo's designs by the Ottomans, when they are in the Archives in E07S01.
In S2, when we first meet Alfonso and his father, Sixtus says Naples is the last rempart against the Ottomans threat.
So,I acted all surprised in S3 when the Labyrinth doctor aks Riario if the Pope has agreed to lead the Crusade, because it seemed to pop from nowhere, but it seems not ?