Critical Role's Matt Mercer is giving up control of a core pillar of the crew's booming business

• Critical Role's long-awaited fourth campaign kicks off on October 2.
• One big change is that CR's chief creative officer, Matt Mercer, will not be the game master.
• Mercer is handing over control of the long-term campaign to Dimension 20's Brennan Lee Mulligan.

Critical Role's chief creative officer and longtime game master, Matthew Mercer, is making a big change at the team's nerdworld business.

When the team's fourth campaign kicks off on October 2, it won't be Mercer sitting behind the game master's screen. Instead, helming the campaign — a long-term staple of Critical Role's streaming business — will be Brennan Lee Mulligan of "Dimension 20" fame.

The two men have forged a formidable alliance, guest-starring on each other's shows while cornering a sizable chunk of the tabletop touring business. The eight-member CR crew has filled arenas from Wembley in London to megashow venues in Australia, while "Dimension 20" sold out Madison Square Garden for their January gig.

"We've been enormous fans of Brennan's for many years now, and when it came to giving both Matthew Mercer and the world of Exandria a bit of a breather, Brennan felt like the perfect storyteller to take our community somewhere entirely new," Critical Role CEO Travis Willingham said in a press release.

The show's fourth campaign will air on CR's streaming platform, Beacon, and its YouTube and Twitch channels. The campaign will also be set in a new world, not Mercer's world of Exandria, in which the first three campaigns occurred.

"What a gift, a privilege, and an honor to be invited behind the screen of Critical Role for this next epic adventure," Mulligan said in the press release. "Every collaboration we have had together has brought nothing but sheer joy, and Campaign 4 will be no exception."

CR has not announced if its fourth campaign will still use "Dungeons & Dragons," the Wizards of the Coast-owned system that the crew first started playing on stream. The CR team is now promoting "Daggerheart," its answer to the "D&D" juggernaut. Its main cast has rolled out content on-stream to promote the now sold-out game.

"We're not just turning a page — we're starting a whole new book," Marisha Ray, CR cofounder and the team's creative director, said in the press release.

Ray also teased new content in a June interview with Business Insider backstage at the crew's Melbourne show. There'll be more "fun, out-of-the-box" content airing on Beacon for CR subscribers, she said.

"We have a lot of ideas for shows and stuff that we want to do. It's really just making sure that not just the cast, but also the production team, isn't overextending itself too much," Ray told BI.

"And we really want to do more shorter-run series as well with 'Daggerheart,'" she added. "I think it lends itself very well to short-run series as well as genre-bending, and doing more things that we can experiment with."

CR has not said if all the cofounders will participate in the crew's fourth campaign, which may mark a significant departure from 10 years of streaming together.

Still, the CR cofounders are being kept busy with their two Amazon-backed animated series. "The Mighty Nein" drops on November 19 on Prime Video.

Meanwhile, "The Legend of Vox Machina," which raised more than $11 million in its initial Kickstarter funding run, has been renewed for a fifth and final season. The fourth season of "Vox Machina" is slated for 2026.