The billionaire recently withdrew from the planned takeover, saying Twitter failed to prove that spam bots make up less than 5% of active users on the website.
Twitter reportedly hired a big law firm ahead of a likely court challenge in a Delaware court. The company said it is confident it will prevail and force the sale.
Mr. Musk says the legal fight will backfire on Twitter.
“They said I couldn’t buy Twitter; then they wouldn’t disclose bot info; now they want to force me to buy Twitter in court; now they have to disclose bot info in court,” Mr. Musk tweeted in a meme featuring four photos of him laughing.
Moments later, he posted a picture of martial artist Chuck Norris playing chess with the message, “Chuckmate.”
Mr. Musk hadn’t tweeted since Thursday.
The legal spat grew serious in the interim, with Mr. Musk’s lawyers saying Twitter made “false and misleading representations” when Mr. Musk agreed to buy the company in April and those representations amounted to a breach of the deal.