I have the same problem, (a swarm of spambots from Tor) and I have followed the tips listed in this thread, increasing rate limits, reducing topic/post numbers for new users, etc.
I’ve slowed the onslaught of posts, but I still have to delete them manually, and I’m still getting dozens of spambot users per hour signing up.
In my case that it would be very easy to stop their posts appearing with a content filter of some kind - all the posts contain content in Korean, and also spelling variations on bam war5 . com (not hyperlinked).
I couldn’t find anything in this thread or others about content filters to mark as spam - is there any way that posts containing this recurring text could be automatically rejected/deleted?