For "obZen", Haake returned to the drum kit most notably with his performance on the song "Bleed". In an interview for Gravemusic.com, Haake stated, "['Bleed'] was a big effort for me to learn, I had to find a totally new approach to playing the double bass drums to be able to do that stuff. I had never really done anything like that before like the fast bursts that go all the way through the song basically. So I actually spent as much time practicing that track alone as I did with all of the other tracks combined. It's kind of a big feat to change your approach like that and I'm glad we were able to nail it for the album. For a while though we didn't even know if it was going to make it to the album." Hagström also stated, ""obZen" is one of the most highly technical offerings the band has ever put to tape". "Revolver Magazine" confirms this statement: "At first listen, "obZen" seems less challenging to the listener than some of the band's other records, and most of the songs flow smoothly from one syncopated passage to the next. However, careful examination reveals that the material is some of the group's most complicated".