Originally Posted by Undead Fantasy
I still think he can't beat Zamasu and he will eventually get tired and killed.
With all the different ways this could go, and the possible ways Black and Zamasu could succeed, this is not even a plausible path. Jiren wouldn't be stupid enough to keep pounding on Zamasu until he gets tired. Even if Zamasu didn't tell him he was immortal, I'm sure Jiren would figure that out and fallback. (Unless he really is a caveman.)
And with their power difference, it would take a LOT for Jiren to get tired out.