Available on Sourcehut and GitHub.
Here are a few example rules you can use. If you have a good rule you think might help others, please get in touch.
ua:\s+ - Block empty user-agent strings.ua:.+?(?i)bot.+? - Block anyone with the word 'bot' in the user-agent.payload:.+"comment":"([^"]{0,30})" - Block short comments from being submitted (between 0 and 30 characters).