I do not remember the details, only that it involved both Kerry and his girlfriend/wife and some magick book/spell gone array, but Ronnie James Dio talked about it in an interview once when he was asked why he'd appear on a Christian album like 'Seeds Of Change' and sing songs like 'Mask of the Great Deceiver' and 'To Live for the King' when he had just joined Black Sabbath. Ronnie wasn't aware that Kerry had become a Christian since Livgren asked him to sing on the record until it was 'too late'. It freaked him out completely once he put 2 N 2 together in the studio! Apparently, those 2 guys had connected sometime prior to the 'incident' when Kerry was still heavily into the occult, which Dio is/was, too, to a degree (don't know if Blackmore introduced him to it or whether it goes back further...). Strange story...