Interesting to note that Cloudflare went a few steps further and not only tried to invalidate the patent but also took the troll to the state bar association for disciplinary action. I'm not sure there is an outcome on that yet, but I think the strategy to do everything you can to destroy the trolling entity that sued you is a great one in this case. Might even consider filing several lawsuits and complaints to overwhelm a small scale troll.

Or if you're the size of Cloudflare, bully them in other ways. In this example it's an operation setup by just two lawyers, easy to make them regret going after you if you make their work impossible. You could for example hire away their legal staff, delay things for ages, screw with the personal life of the two founders. They can't keep a small business afloat for very long if you dedicate some resources to screwing with their operations.

Might even just sue their clients for something else (one of your patents for example). In this case the client is a small firm in Germany, they would be in a very bad place if they got sued in the US home district of Cloudflare and had to defend. High probability that they would put pressure on the lawyers to drop the troll suit.