"'SECTUMSEMPRA!' bellowed Harry from the floor, waving his wand wildly. Blood spurted from Malfoy's face and chest as though he had been slashed with an invisible sword. He staggered backward and collapsed onto the waterlogged floor with a great splash, his wand falling from his limp right hand." (The Half-Blood Prince, p. 522.)

What an amazing hex Sectumsempra is! It is as if it makes one's wand a very long, weightless, invisible, incredibly sharp sword. The effect this would have on an enemy is stunning, not only because of the damage it inflicts but because the hex is so little-known. Kudos to Snape for figuring this one out indeed! Such a ruthless hex!

Do you think we will see it again in book seven? Wouldn't mind seeing it used on LV after the horcruxes are destroyed, especially if Harry is to avoid using the unforgivable curses and still kill LV. And I wouldn't be surprised seeing as how JKR had Harry use a sword already to kill the Basilisk summoned by LV. It would fit. Comments?