The disappointment of Cold Lake prompted Fischer to fire Amberg, who was most responsible for the disappointing effort. After taking about a year off, Fischer regrouped and hit the studio to record Vanity/Nemesis, which was released in April 1990. While the album was well received by critics, it failed to repair the damage to Celtic Frost's reputation done by Cold Lake. Fans rejected the album, which would be the band's last full-length effort for 16 years. After a brief tour, Fischer decided to shut down Celtic Frost for good, though a compilation entitled Parched with Thirst I Am and Dying was released in early 1992. Fischer would take nearly three years off from music before setting out to form another band.
Early in 1995, Tom Fischer met guitarist Erol Unala and the pair formed Apollyon Sun, named after the never-realized final Celtic Frost album, "Under the Apollyon Sun." The band released an EP titled God Leaves (And Dies) in the summer of '98, followed two years later with the release of Sub, the band's only full length album. Apollyon Sun's sound was generally well received, with fans enjoying the industrial metal sound laced with elements of Celtic Frost's black metal legacy. It was also around this time that Fischer's autobiographical novel, Are You Morbid?: Into the Pandemonium of Celtic Frost, was published. The majority of the novel was written during Fisher's hiatus from music, and finally published in 2000 by London-based Sanctuary Publishing. The following year Fischer and Unala began working on material for a studio album from Apollyon Sun with the tentative title Flesh. The album was never completed, however, and Fischer reunited with Martin Ain to reform Celtic Frost in 2001, inviting Unala to join, as well.
With Ain and Unala involved, Tom Fischer set out to evolve the Celtic Frost sound into a darker, heavier group. These efforts proved difficult, however, as an album would not be released for almost five years. In the meantime, Fisher was invited to take part in Probot, a project founded by Nirvana drummer and Foo Fighters frontman Dave Grohl to pay tribute to his heavy metal influences. An album resulted, released in 2004, with Fischer singing on one of the tracks. Grohl had recorded the instrumentation for all the tracks several years earlier, and wanted legendary metal singers to finish the project. Besides Fisher, the Probot album also featured vocal contributions from Cronos (Venom), Lemmy Kilmister (Motorhead), King Diamond and Snake from VoiVod.
In May 2006, Celtic Frost released its sixth and final studio album, Monotheist. Critics and fans alike welcomed the first new Celtic Frost material in over a decade, and the album has been consistently included among the top 10 albums of the 2000s by various metal publications. The album was released on Fischer's own label, Prowling Death Records, and distributed through a licensing deal with CenturyMedia. Monotheist restored the loyalty of longtime Celtic Frost fans and spawned its longest and highest-grossing tour. The band stayed on the road for over a year, wrapping up in Mexico City on October 13, 2007. The band has consistently declined requests to reunite for shows ever since.
With his career as Celtic Frost's frontman in the books, Fischer has been focusing on his third band, Triptykon, since September 2008. The band has released two studio albums to date, with a third scheduled for release on April 14, 2014. While Tryptikon is a new band, Fischer has often stated his goal for the project to be a continuation of the Celtic Frost legacy. He has often described his work in Triptykon as a continuation of Celtic Frost.