We played Ravenloft when it first came out (this would probably have been very late 1983, or early 1984). TPK, one of only two our campaign has had in 25 years. Let me tell you how. As you may know, there are multiple ways in which one can permanently whack Strahd in this module, but only one particular way will work in any particular running of the module. Our DM determined that it was going to be the "Sunsword" method, and the only candidate sword in the party was that belonging to our half-orc fighter/cleric.