This is clearly getting ridiculous  Snape knew how to cure Scermptsa  a spell mentioned only in the HBPs book clearly not a spell mentioned or taught in school  Who would know it  The creator of the spell Snape  He also knew about Levicorpus  He is also extremely suspicious when he Slughorn praises Harry as a great Potionmaker and knew that his old book was still in the cabinet  Harry says it himself Snape didnt say anything because he would trip up Dumbledore The book is assigned to all sixth years  We have no proof at all that Lily ever befriended Snape  we see her defend him but Snape rebuffs her  Lily calling herself a HalfBlood when she is clearly a Muggleborn  And Prince  That seems ridiculous  The book also contians a lot of Dark Arts spells ndash Sirius says that Snape knew more curses in his frist year than half of the seventh years  lily in the Dark Arts  Not probabe