While the magic you invent is always stunning and original, sometimes - I will admit - it gets too strange for me, even though certainly, if one takes a magical world seriously, magic would be as all-pervasive as you write it. But in this chapter, you used magic so very well to enhance the action and to build-up the suspense, I was literally spell-bound reading it. The Cobra Curse is awesome, also the entire interaction between Snape and Harry deflecting it. I loved the amethyst splinters in the magic that the imposter would use to rid Draco of his intendity. Amethyst is the temperance stone, cleansing mind and soul from all kinds of obsessions - but you know that, don't you ;-). Thanks so much for writing.