Encountered the same problem again, trying to finish ultra and im at chaos gate. Cannot use wishes / magical writing sets, both of them results in crash. Ill have a look at it tomorrow.
Has been a tough run, had to kill filk and emperor moloch twice due to magical writing set crash earlier. Feels scummy to load backup saves, even thou it is resulting from a crash :(
Copied the backup save @ D50 in case someone wants to see whats up, dont want to put it on public link.