combination of speed and heaviness," and later said that the "writing is really aggressive and fast, while Jeff likes things to be fast, but with melodies and grooves. In making this album, we seemed to share the same vision from song ideas to titles; when we get together as Slayer, it just happens, nothing is contrived, it's not thought out, we just do it, and we did that with this new album." Lombardo said that Hanneman's writing and performance had "gone back to this great punk energy, especially with 'Psychopathy Red'." Allmusic said that it expressed moods such as Harshness, Fiery, Confidence, Rowdiness, Aggressiveness, Rebellious, Cathartic, Anger, and Hostility. It also is categorized in genres like speed metal and heavy metal. Thom Jurek said Lombardo's percussion beats "are WAAAAAAAY up in the mix," and said that "you can understand every word, even on the thrashers" about Tom Araya's vocal style. "[T]he guitars are simply further down in the mix and sometimes it becomes difficult to discern Araya's bass. Therefore, the first listen or two to World Painted Blood might be a bit confusing for the seasoned Slayer fan, but that changes quickly, and the sound of those drums blasting in one's head will become a more than welcome presence in the mix." The album's title track was said by band members to be the continuation of "Final Six", which was an outtake from their previous album. "Final Six" origins deal with the apocalypse. "Human Strain" deals with apocalyptic origins as well. The track was explained by guitarist Jeff Hanneman to initially be about the human race dying off by a mutative disease. The title of "Public Display of Dismemberment" refers to the consequences that countries outside of the United States give to citizens for crimes. Tom Araya said that "Unit 731" is "very similar to Josef Mengele in the sense that it was a medical unit in the military, which was a Japanese military unit, actually. They did kind of the same thing; they tested the limits of the human body and recorded it for scientific purposes." "Playing With Dolls" is about a child witnessing a serial killer. "Beauty Through Order" is about Elizabeth Báthory, the most prolific female serial killer. Jeff Hanneman explained: "I've been meaning to write a song about that for a long time. I couldn't figure out the angle, I was thinking, 'How does a woman