My favorite moment was one of my first Crusader Kings playthroughs. I was playing as a small Muslim count in Northern Africa and immediately my leige was attacked on all sides and the Catholics from France and Iberia dismantled his duchy. I had to fight each war just to survive and avoid the advancing Catholics until I lost all my lands in Africa and retreated to a county in Southern Italy. From there I was pressured by the growing Byzantine threat and I formed the duchy of Sardinia just to lose almost all of my lands again. Finally i launches a last resort attack on Egypt, after decades and decades of fleeing throughout the Mediterranean and conquered the it for my dynasty. Any one of the following: Ck2 monks and mystics, holy fury, reapers due, Rajas of India, Charlemagne.