Ronnie James Dio infused Black Sabbath with incredible energy when he joined the band in 1980. Heaven and Hell is an absolute classic, and just one year later they followed it up with Mob Rules. Drummer Bill Ward checked out midway through the Heaven and Hell tour, so Vinny Appice took his place behind the kit. When they released Heaven and Hell Ozzy had yet to kick off his solo career, but by the time of Mob Rules he was scoring massive hits and packing arenas. The competition was probably a good thing, and tracks like "The Sign of the Southern Cross" and "The Mob Rules" rank up there with anything in the Sabbath catalog. This was the last album with Dio for over a decade, and it began a long period of decline for Sabbath.