Ask HN: How to deal with a negative SEO campaign?

Hey all, I'd be really appreciative of any advice the HN community has in dealing with a negative SEO campaign against our site's blog (blog.stylekick.com). Whoever is hitting us is using multiple registrars in multiple geographies. Right now my options are to reach out to individual registrars, or use Google's disavow tool. The campaign seems to be ongoing - so I'm not sure if the disavow tool is our best bet.