I am not so sure where exactly the platform is. I haven't played this game in like 3 years and I only played it about 3-5 times before and I never finished the game once yet but I think the next to last time I played it, I got into the beginning part of the chamber and I was too afraid to go in because of all of the spiders. I might have said this before in another post a long time ago but I am not so sure. I answered a post about the platform but now I don't exactly remember what I was talking about since I haven't played the game for awhile. I know about the one by the diffindo challenge area and the other one I think on the right side all the way on the right where you cast alohomora. I think it is on the left because I do remember a spongify symbol there but I don't know if it is the same one because I do remember different spongify symbols throughout the grounds and I know one of them didn't work for me for some strange reason. I heard that you are supposed to cast another spell on it before you use spongify and I think that in one of the my early games before I got to the spongify part that I think I did cast a spell on something like that but I don't remember now if that was the same part or it could have been a different part. Where exactly is the platform and what do you have to do about it?