"The Board of Governors believes that Hogwarts should focus its teaching this term on-for this purpose, the staff should make efforts in the following areas-if we do this, the outcome will develop in that direction, which is unacceptable, so we must do this-"
In the Great Hall at Hogwarts, the entire staff was present. Lucius Malfoy sat at the long table in the front row, listening to an old man on the Board of Governors whom he had paid a fortune to buy off spout meaningless drivel. He calculated the time. It was almost time to leave the Great Hall for the bathroom.
"I'll be right back." With those words, Lucius swaggered out through the Great Hall's side door. If the plan went smoothly, he would return in about fifteen minutes, while news of Harry Potter being attacked in the Astronomy Tower would take at least another half hour after his return to reach this place.
After walking into the bathroom at an unhurried pace, he immediately cast a Disillusionment Charm on himself, poked his head out, and carefully checked both directions for half a minute, using Detection Magic as well. Excellent. There was no one around, only some student's pet that had slipped out of the dormitory for a stroll.
Locking the door, stripping, drinking the Mist Form potion, magically storing another potion he would need shortly inside his mouth while waiting for the first to take effect, then disposing of the potion bottles with a Vanishing Spell-Lucius performed it all in one fluid sequence. A cloud of transparent mist soon drifted out through the bathroom window. In daylight, someone with exceptionally good motion vision might have discerned a human shape upon close inspection, but it was night. Unless someone kept magical detection active constantly, he would not be