I got caught up in an unwinnable fight today. It was not fun at all. I went about 15 rounds before I just force-closed the game to take some time off.
The enemy Golden Son Assassins just kept casting Endure, I kept healing and using Pharaoh Eddie's Invincibility (which doesn't always prevent damage BTW). They probably would have eventually wore me down had I not quit anyway, but it sucked. My screenshot shows the fight after about 8 rounds or so (5 invincibilities stacked on Pharaoh Eddie