For Brendon Small, cortex-squashing pressure sort of comes with the territory. Small is the creator of the breakaway hit TV show Metalocalypse, writing the scripts, voicing several characters, and because the show concerns a fictitious death metal band, Small composes all of the ferocious and unbelievably catchy music for each episode. The show is a bona fide cultural phenomenon, first attracting a rabid cult audience (are cult audiences any other way?), then finding seismic popularity in the mainstream. Mad Men’s Jon Hamm, award-winning documentary producer Warner Herzog and Hall of Fame inductee Slash are a few of the legion of celebrities who have proclaimed their enduring love of Metalocalypse. The show, featured on the Adult Swim cable channel, begins its ravenously-anticipated fourth season on April 29 with more preposterous plots, scorching humor and the show’s most impressive lineup of celebrity voices yet. In fact, both Hamm and Herzog will be appearing in Season Four, along with an astonishingly diverse and talented cast of other actors, comedians and, of course, musicians.