Suffice it to say 1986 was a game-changing year for thrash music and heavy metal, with Slayer's masterpiece "Reign in Blood" becoming the standard-bearer as one of the greatest thrash albums of all time.

Released by Def Jam records on Oct. 7, 1986, Slayer's third studio album came out seven months after Metallica's "Master of Puppets", and, while "Master of Puppets" was fast and heavy, Kerry King, Jeff Hanneman, Tom Araya and Dave Lombardo made sure "Reign in Blood" took heavy and fast to a whole new level.

At just 28:58 in length, it was one of the shortest records ever made (it could fit onto one side of a cassette tape), but that was all by design.

"If we do a verse two or three times, we're already bored with it," said Hanneman, who died in 2013 after dying from alcohol-related cirrhosis of the liver. "So we weren't trying to make the songs shorter—that's just what we were into."

While the songs were shorter than on Slayer's hugely-underrated sophomore Hell Awaits, the furiously fast riffs, controversial and violent song matter, as well as Lombardo's frantic drumming were still there.

The key difference was producer Rick Rubin.

Rubin, who owned Def Jam Records, was well-known at the time as a top-notch rap producer for acts like LL Cool J and Run DMC. He met with the band in Europe and convinced them to join his label and let him produce the record (even though he'd never worked with a metal band before), while giving the Slayer full license to write whatever they wanted.

Through his official account on Genius, a music annotation site, Rubin gives some insight into recording Reign in Blood.

"In terms of writing, I’d say the Reign In Blood album was pretty close to complete when they came in," said Rubin. "I think we just stepped up the recording from what they had done independently before that. It was really more the engineering."

Renowned engineer Andy Wallace, who later produced Nirvana's Nevermind, had a huge hand in creating that crisp, clear, in-your-face thrash sound, which had way less reverb than on Slayer's previous two albums.

"Andy Wallace did it, which is what later got him in with Nirvana, absolutely. A hundred percent. It was insane. It was punk energy but with a precision that punk rarely ever had. It was much tighter than punk," said Rubin about

Most of the songs on Reign in Blood were brutal, morbid and disturbing for many people back in 1986, but none more so than "Angel of Death", a Hanneman track about Nazi SS officer Dr. Josef Mengele, who performed sickening experiments on Jews at Auschwitz, the Nazis most infamous concentration camp.

With it's no-holds barred look at Mengele's work, Columbia records (Def Jam's distributor) refused to distribute the record. Many of the record label owners were Jewish, so this shouldn't have come as a surprise. However, Geffen Records did distribute it, but because of the controversy, Reign in Blood was not on the their release schedule.

It should be noted what a key contributor the late Hanneman was for Slayer back then.

He wrote the music for every track on Reign except for "Piece by Piece", a King composition. Hanneman also contributed lyrics the intense lyrics for "Angel of Death" as well as "Necrophobic". He also had a hand in the words to "Criminally Insane" and "Raining Blood". There was a massive hole in Slayer when he died in 2013 of liver failure.

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