Heaven & Hell will play a special set at the High Voltage festival next month to honour their former singer Ronnie James Dio.The band - Tony Iommi, Geezer Butler and Vinny Appice - will draft in former Deep Purple / Black Sabbath vocalist Glenn Hughes and Masterplan frontman Jorn Lande for the gig at London's Victoria Park on July 24. "Ronnie's passing has left a huge hole, we hadn't anywhere near finished what we set out to do as a band together," said Tony Iommi. "He was so looking forward to the European tour and we hope this appearance will go some way to fulfilling that."Tickets are on sale now from www.aloud.com.