The Genetic Opera's director Darren Lynn Bousman to create The Devil's Carnival, a cult musical film starring Emilie Autumn, Paul Sorvino, Sean Patrick Flannery, and Terrance in the title role of Lucifer.

[5] Terrance and Saar composed the music for the film, which Ain't It Cool News described as having "...a frantic kaleidoscope-Elfman vibe, but with a much more devious slant.

[9] The duo released their first online trailer for the project on March 10, 2016, which featured the voice of The Devil's Carnival collaborator and Sons of Anarchy star Dayton Callie.

[13] The videos featured performances by cult music stars like Arch Enemy’s Alissa White-Gluz as Pretty Lavinia, Aurelio Voltaire as lothario wife-killer Unwed Henry, and Chibi, front woman of The Birthday Massacre, as Sweet Rosalie, an "escaped mental patient who leaves a trail of dead in her wake.

"[19] The tour hit 30 American cities and re-enacted the music of 1816 by way of a historical wake for the fictitious A. Finneus Buck, where "Fans flocked to the event dressed in their best funeral attire, ready to pay their respects to the deceased.

That same March, Terrance and Saar embarked on a research road trip where they followed in the historical footprints of the Donner Party and invited fans to be a part of the journey by watching live streaming videos.

The new album veered into more "zany" territory with songs like "The Devil In Camp," about the Donner Party's most infamous member, Lewis Keseberg, "presented in the form of 50's surfer music.

In April, Terrance and Saar began recording their third studio album, The Killing Place, which was released in November, 2018, and featured cover versions of popular tunes involving murder, including a double kick gunslinger take on Foster The People's “Pumped Up Kicks,” about a school shooting, and a rock 'n' roll chain gang rendition of “Jenny Was a Friend of Mine” by The Killers, based loosely on the 1986 murder of Jennifer Levin by Robert Chambers.

[30] The Killing Place also included a revamp of “In All My Dreams I Drown,” a number written for a scene that was deleted from The Devil's Carnival, but nonetheless became one of Terrance and Saar's most popular compositions.

Just You, The Boys & A Piano,” where they encouraged fans to “Dress To Kill.”[32] The Anti-Recital was held at a series of publicly undisclosed locations that ranged from oddity shops to tattoo parlors, and recording studios to small theaters.

Ghastly Grinning described the Anti-Recital experience as “... casual and familiar, it’s a cocktail hour at a friend’s house, yet the dress code and lack of technology lends it a bit of finesse, a grace and dignity that calls to mind the feel of exclusivity, of being included in something much more intimate than a crowded show or auditorium screening meet-and-greet.”[33] In August, Saar and Terrance announced that American Murder Song would be the opening act for the cello rock group Rasputina on their West Coast US tour.

In March 2017, they took a research and writing road trip where they followed the historical trail that the Donner Party took in 1846, inviting fans to participate in the journey with them via live video streams.

In March 2018, for American Murder Song's "Two-Year Anniversary Feast," Saar and Terrance offered fans chances to play The Donner Party Board Game with them, as well as be featured on their The Killing Place album.