How about this:
1) New users who register have a five minute to thirty minute cooldown before they may post again.
2) New users under this restriction who attempt to make fundamentally the same post more than twice are automatically banned and posts deleted
3) To remove this restriction, a user must click on a 'verify me' button and answer a question. Such questions can be "What does FTB stand for", "What version of Minecraft did FTB originally get created for" and the like. Easy questions that almost everyone already knows the answers to, but are not able to be discerned by a robot. Most bots aren't able to click on a 'verify me' button post-creation if it is in your profile settings, and a question like that is very difficult for a bot to answer.
Alternately...
Require email verification to be able to post. Ban any accounts with emails from known bad domains preemptively.
1) New users who register have a five minute to thirty minute cooldown before they may post again.
2) New users under this restriction who attempt to make fundamentally the same post more than twice are automatically banned and posts deleted
3) To remove this restriction, a user must click on a 'verify me' button and answer a question. Such questions can be "What does FTB stand for", "What version of Minecraft did FTB originally get created for" and the like. Easy questions that almost everyone already knows the answers to, but are not able to be discerned by a robot. Most bots aren't able to click on a 'verify me' button post-creation if it is in your profile settings, and a question like that is very difficult for a bot to answer.
Alternately...
Require email verification to be able to post. Ban any accounts with emails from known bad domains preemptively.