Make it a new rule, that new accounts can only upvote, and won't be able to comment/post until after a certain period of time that Mods deem appropriate, be it 10 days/two weeks[or however many days you Mods decide upon].

Most soycialist trolls are after instant gratification, if they find out there's a waiting period of 10 days/two weeks[however many days Mods decide upon] a lot of them will go "ah, fuck it" and not even bother making an account.

Sure it wouldn't deter all trolls, I never said it would, but I think it would stop a good number of them at least.