Some things can be counted on at a Slayer recording session. "Can I interest you in something fast and aggressive?" asks producer Greg Fidelman. He's sitting beside guitarist Kerry King at the Pass Studios in Los Angeles, where Slayer are working on a still-untitled album planned for a summer release, and cues up a new metal track with the working title "Build Up." King is ready to thrash.

He's already tapped the Jägermeister machine upstairs, and is now bent over a custom camouflage guitar,...