When Fighting the Wights and the Master in the Dark Castle, I place a sleep spell on the Master to avoid killing him and then proceeded to kill everything else, however I reach a point where the master woke up and so tried to place a Fog cloud on him so that I could wipe the last Wight. At this point the game freezes and no Fog cloud appears. No matter how or when I do this it always freezes when trying to use the Fog Cloud scroll. I do have a visual capture at the point it freezes. The only way to prevent the game from freezing is not to use the Fog Cloud scroll.
I am unsure if it is the sequence of Sleep spell then Scroll of Fog Cloud, or it is the sequence in this area, or just the Scroll of Fog Cloud. I do recall using the Scroll of Fog Cloud before.