The series stars Marisha Ray, Ashley Johnson, Laura Bailey, Travis Willingham, Liam O'Brien, Taliesin Jaffe, and Sam Riegel as the players with Matthew Mercer as the Dungeon Master.

The campaign begins two months before the Apogee Solstice, a celestial event which influences the ley lines of Exandria and magnifies magical abilities.

They eventually discover that the gods crafted Ruidus to imprison an ancient evil known as Predathos and that the Ruby Vanguard – founded and led by Martinet Ludinus Da'leth – seek to free this entity during the Apogee Solstice.

[5] The Exandrian Accord brought together nations and factions from across the world to form a military alliance in opposition to the forces of Ruidus;[6][7] Bells Hells, along with the adventuring parties Vox Machina and Mighty Nein, lend their aid as coordinated strike teams against various Ruidian targets.

[10][21] Mercer noted that both Johnson and O'Brien brought character concepts they were toying with for Campaign 3 over to Exandria Unlimited, where they had the chance to develop them with Aabria Iyengar.

[22] Additionally, Mercer has brought back several player characters from previous campaigns as NPCs such as Vox Machina's Keyleth and Pike and The Mighty Nein's Caleb and Beau.

[67][70] The show was placed on an unplanned hiatus in January 2025 as a result of the California wildfires in the Los Angeles metropolitan area where the studio, cast and crew are located.

[28] The episode then picked up with Aabria Iyengar as the Dungeon Master with Mercer, Daymond, Aimee Carrero, Anjali Bhimani, and Erica Lindbeck reprising their player roles from the spinoff Exandria Unlimited: Kymal.

[82] At the end of Episode 98, Mulligan took Mercer's place – his monologue was the opening of a magical projection of the past witnessed by Bells Hells and Ludnius Da'leth.

[34][83] Critical Role then announced the next episodes would be a three-part special titled "Downfall" with Mulligan as the Dungeon Master and the player cast as Bailey, Jaffe, Johnson, Noshir Dalal, Nick Marini, and Abubakar Salim.

[84][85][86] "Downfall" is set over a century into the Calamity; while officially part of the third campaign, it is advertised as a standalone special that does not require prior knowledge of Critical Role or Exandria Unlimited.

[87] Cheryl Teh of Business Insider highlighted that "Downfall" focuses on the fall of the magocracy Aeor and suggested this will "allow Mulligan to flex his storytelling chops, perhaps reprising some elements of his first EXU: Calamity run".

[91] Bailey noted that "it wasn't like jumping in from ground zero" due to recently reprising their older characters on The Legend of Vox Machina and The Mighty Nein animated series.