[sotspecatcle]

    if ($http_user_agent ~* "BadBot") {
        limit_rate 1k;
        default_type application/octet-stream;
        proxy_buffering off;
        alias /dev/zero;
        return 200;
    }

[Avamander]

I recommend you use gzip_static and serve a zip-bomb instead. Frees up the connection sooner and probably causes bad crawlers to exhaust their resources.