Matt Pike (right) of High on Fire has checked into rehab.

As part of Sleep, Pike set the bar for stoner rock with hallucinogenic doom metal so sludgy it sometimes out-Sabbathed Sabbath. After their break-up in the ’90s and throughout their sporadic reunions, they’ve become almost more a legend than a band. That legend continues to grow, thanks to war stories like the time in 1995 that record execs refused to release their third album, Dopesmoker, because it was one hour-long song. Under the pressure of endless label blowback, the band split into Om and High on Fire.

Just last week, Sleep headlined at the Scion A/V Rock Fest in Tampa, where cake was brought onstage at the end of the set to celebrate Pike’s birthday.

It’s now been 14 years since Pike formed High on Fire in Oakland. They just released their latest album, De Vermis Mysteriis, in spring. That it debuted at #61 on the Billboard charts despite the fact that HOF’s music is even harder than Sleep’s ever was is a testament to the fact that it is also hookier and simply undeniable. What Pike has created with the band represents nothing less than the future of metal.

The band’s other two members, drummer Des Kensel and bassist Jeff Matz, released a statement saying “High on Fire would like to thank everyone involved with the Rockstar Energy Drink Mayhem Festival for the opportunity to be a part of this year’s tour. We regretfully will have to bow out as our friend and bandmate begins his recovery, but very much appreciate having been asked to be a part of this summer’s festival run.”

Reigning biggest metal tour the Rockstar Mayhem Festival has announced its line-up for this year, which features headliners Slipknot and Slayer, along with Anthrax, the Devil Wears Prada, As I Lay Dying, High on Fire and Whitechapel. The 26-date tour begins on June 30 and comes to Shoreline Amphitheatre in Mountain View the next day, July 1.

Another as-yet-unrevealed band referred to so far only as a “major special guest” will be announced on March 5. Tickets go on sale April 6.

Slayer and Anthrax have joined up several times over the last couple of years for the historic “Big 4” shows that saw them touring with Metallica and Megadeth, uniting the top thrash bands for the first time. This tour will be different, as Slayer will be on the main stage, while Anthrax will be headlining the secondary Jagermeister stage, which is getting a huge upgrade.

Another interesting addition is High on Fire, the offshoot of legendary San Jose stoner-metal band Sleep. Their 2010 album Snakes for the Divine was the best record of frontman Matt Pike’s career, and may finally make him more famous for the albums he did finish than the ones he didn’t.