Black Sabbath are playing just one concert in 2012, according to a message they posted to their fans via Facebook and Twitter. Although the original band – Ozzy Osbourne, Tony Iommi, Geezer Butler and Bill Ward – were supposed to tour Europe this summer, they had to change their plans when Iommi was diagnosed with lymphoma.

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Bill Ward’s involvement in the reunion is now not certain, due to ongoing contractual disagreements. For now, they are only going to play one show, on June 10 at the U.K.’s Download Festival.

Instead, “Ozzy & Friends” will fill in for the rest of Sabbath’s previously scheduled festival and headlining dates.  The “Friends” band will include Geezer Butler (who has played in Ozzy’s solo band in the past) and Ozzy’s former guitarist Zakk Wylde.  Slash will be with the band on select dates, and other special guests will be announced later. The band’s statement says that “Tony Iommi continues to make excellent progress and is looking forward to getting back out on the road.”

Sabbath announced their reunion late last year, and they’ve been working on a new studio album, to be produced by Rick Rubin.