Writing and style
Hanneman, Araya and King were the main contributors for the band's lyrics
Slayer is considered a thrash metal band. In an article from December 1986 by the Washington Post, writer Joe Brown described Slayer as speed metal, a genre he defined as "an unholy hybrid of punk rock thrash and heavy metal that attracts an almost all-male teen-age following". Describing Slayer's music, Brown wrote: "Over a jackhammer beat, Slayer's stun guitars created scraping sheets of corrosive metal noise, with occasional solos that sounded like squealing brakes, over which the singer-bassist emitted a larynx-lacerating growl-yowl." In an article from September 1988 by the New York Times, writer Jon Pareles also described Slayer as speed metal, additionally writing that the band "brings the sensational imagery of tabloids and horror movies" and has lyrics that "revel in death, gore and allusions to Satanism and Nazism." Pareles also described other "Big Four" thrash metal bands Metallica and Megadeth as speed metal bands. Slayer's early works were praised for their "breakneck speed and instrumental prowess", combining the structure of hardcore punk tempos and speed metal. The band released fast, aggressive material. The album Reign in Blood is the band's fastest, performed at an average of 220 beats per minute; the album Diabolus in Musica was the band's first to feature C♯ tuning; God Hates Us All was the first to feature drop B tuning and seven-string guitars tuned to B♭. AllMusic cited the album as "abandoning the extravagances and accessibility of their late-'80s/early-'90s work and returning to perfect the raw approach", with some fans labeling it as nu metal.
King and Hanneman's dual guitar solos have been referred to as "wildly chaotic", and "twisted genius". Original drummer Lombardo would use two bass drums (instead of a double pedal, which is used on a single bass drum). Lombardo's speed and aggression earned him the title of the "godfather of double bass" by Drummerworld. Lombardo stated his reasons for using two bass drums: "When you hit the bass drum, the head is still resonating. When you hit it in the same place right after that, you kinda get a 'slapback' from the bass drum head hitting the other pedal. You're not letting them breathe." When playing the two bass drums, Lombardo would use the "heel-up" technique.
In the original lineup, King, Hanneman and Araya contributed to the band's lyrics, and King and Hanneman wrote the music with additional arrangement from Lombardo, and sometimes Araya. It is unclear why Lombardo has never received any writing credits in Slayer's history. Araya formed a lyric writing partnership with Hanneman, which sometimes overshadowed the creative input of King. Hanneman stated that writing lyrics and music was a "free-for-all": "It's all just whoever comes up with what. Sometimes I'll be more on a roll and I'll have more stuff, same with Kerry – it's whoever's hot, really. Anybody can write anything; if it's good, we use it; if not, we don't."
When writing material, the band would write the music first before incorporating lyrics. King or Hanneman used a 24-track and drum machine to show band members the riff that they created, and to get their opinion. Either King, Hanneman or Lombardo would mention if any alterations could be made. The band played the riff to get the basic song structure, and figured out where the lyrics and solos would be placed. King, Hanneman, and Araya tended to have different lyrical influences. King's lyrics are generally anti-religious; Hanneman's lyrics dealt with Nazis, religion, warfare and similar topics; Araya's lyrics usually dealt with topics that could be considered less controversial than King and Hanneman's, such as serial killers and warfare.