I host a WordPress blog that has been hit with a huge amount of spam in the last three months. I've tried to install several anti-spam plugins that are highly rated, but it doesn't help.
What else can I do or what plugins can I install to stop this wave of spam?
I'm not sure if this question really matches the site, nevertheless I'll answer you.
I can recommend you:
The first one focuses on stopping the spam at your entire site: your comment section, your login section, your registration section, and your trackback section. The second one just checks whether you are a robot or not, both on your registration form and comment form. I use both, and reduced the spam I'm receiving at a total of 98%.
You should note that the first one documents nearly everything. If somebody logs in and gets rejected due to behaviour that matches him as a spammer - in the view of the plugin -, his/her IP address and the username and the password he/she used will be stored and saved. This can lead to some problems with the privacy policy in some jurisdictions.
I switched from native WordPress comments to Disqus years ago - it helped a lot with spam.
However, Disqus is not without its own special brand of craziness, either.
The Akismet plugin (ships with WP, and is free to use once you get a free API key) helps some with native WP comment spam - but botnets don't care how much they spam you.
Sadly - or, perhaps, happily - often the best way to handle comments is to disallow them. If someone wants to react to what you wrote, they can write a blog post themselves, or comment on Twitter/Facebook/Mastodon/etc (ideally, wherever you can interact back).
