[6] In January 2012, Allegaeon went to Lambesis Studios in December 2011, in San Diego, California to record their second full-length album Formshifter.

[11] In 2015, original vocalist Ezra Haynes departed Allegaeon, not citing a specific reason, though it is clear it was not because of internal band issues.

[citation needed] In September 2016, Allegaeon released Proponent for Sentience, the first album with Riley and what was considered their finest work to date.

In October 2016, long time bass player Corey Archuleta announced he would be leaving the band at the end of the year to focus on his law career.

[16] Because of this financial stress, the band launched a fan club through the Patreon platform and have since been focused on continuing to tour and write their next album.

"[33] A month later the band embarked on the "Cancer Culture Over North America Tour 2024" alongside Decapitated, Septicflesh, and Kataklysm.

Lyrically, they deal with scientific themes, exploring things like the theory of evolution and biology, physics, cryonics, dyson spheres, the probability of alien life in the universe, stem cell research,[36][37] and artificial intelligence.

[38] Immediately after, in September 2014, Allegaeon played a string of shows directly supporting Arsis on the band's 10th Anniversary Tour.

Additionally, Allegaeon co-headlined a large tour with Act of Defiance, a metal supergroup featuring members of Megadeth, including guitarist Chris Broderick.

[39] In 2016, Allegaeon also played the Ozzfest meets Knotfest festival in San Bernardino, California[40] and the Winter Warriors tour alongside Battlecross and Necromancing the Stone.