I should point out, by the way, that I had no earthly clue what I was doing. I was still working with the theory that this was all a dream, and that the whole world was under the sway of my godlike powers. As far as I was concerned, the mechanics of spellcasting began and ended with me willing it to happen. At least, that’s how everything so far seemed to work. I was expecting the wall to disappear quietly in a nice, clean puff of smoke, so I charged up my magic horn-blob as much as I could, aimed at the wall of black crystal, and released it all at once. 