Sometimes when smart solutions don't help, and spammers shit all across your website, you can wish you had some hammer to just hit the problem hard. This is why I have written aSpambot. It hits the issue hard, and can be used to quickly put a halt to a flood of spam, and just give you time to find for a more delicate solution meanwhile. As of now, it has two function that I have found extremely useful: block the country by IP and check the IP against the AbuseIPDB database.
I have noticed that sometimes if your website under a heavy spam attack by human spammers, captcha will not help a lot. And if your site is servicing US or EU, and spammers are in Pakistan, then you can ban Pakistan IPs. Or, you can ban ALL ips outside the US! Just be careful not to ban yourself.
Then, I have had spammers from the US. Since US is in my zone of professional interest, I can not ban it. But I can check the IPs against the free AbuseIPDB service. You ust need to log in there and get a key. https://www.abuseipdb.com/about.html
If you are hard hit by forms spam, and need a quick space for maneuver, try aSpambot. You can get the aSpambot module from GitHub. https://github.com/alexrayu/aspambot