“Thill Smitts Terror” continues where “Von Rov Shelter”, the band's critically acclaimed 2009 album, left off, delving more and more deeply into the disturbing world that SLAGMAUR conjures up by combining modern and classical instruments with children's nursery rhymes and fairy tales. It is a world where classically constructed melodies blend seamlessly with aggressive black metal to create a nightmare scenario straight from the pit of hell. Art, as well as music, is an integral part of the whole that is SLAGMAUR - from the sinister masks and costumes the band wears on stage, to the disturbing images used in the artwork for the albums.
Slagmaur was formed in 1997 under the name Norske Synder ("Norwegian Sin" in Norwegian) before changing name in 2006. An official band statement claimed them to be "the darkest and scariest black metal band to ever set foot on planet earth". They have described their sound as "twisted and sinister Black Metal, multi-layered and complex".
The band have also attracted interest for their conceptualized, unusual imagery and live shows which display a theatrical horror aesthetic and bizarre live antics. Their set at the 2017 edition of the Inferno festival, which quickly generated controversy, featured staged executions by hanging as well as a model/stuntman tied to an upsidedown cross which was set on fire at the end of the show, while band members "prowled around the stage, looking genuinely psychotic and to be gaining pleasure from the on-stage executions". The concert reportedly induced strong discomfort among the audience and has been described as "one of the most extreme live acts ever performed", with renowned heavy metal magazine Metal Hammer reporting "It's not easy to shock in black metal today, but Slagmaur did it".