Whoa whoa whoa... hold on...
We don't know anything about how knockers reproduce. And now we're told it is quick and endless?
And we were told earlier that ALL the knockers in the world were coming to this spot. But if they can quickly and endlessly reproduce then that would be completely pointless, as a stream of them could be continually produced from outside the city...
Plus the knockers seem to have completely forgotten how to manipulate wood and stone. They're all about making zombies now.
Just what the hell is going on?