The Headmaster's office became a war room. Within minutes of Ariana's summons, the key players were assembled. Harry, Ron, Hermione, Neville, Luna, and Ginny—the core of the D.A.—stood on one side, their faces a mixture of fear and fierce determination. On the other stood Professors McGonagall and Flitwick, their expressions grim and resolute. Snape lingered by the door, a dark, silent shadow, his face an unreadable mask.
Dumbledore, who had been instantly alerted by his office's wards to their unscheduled arrival, listened intently as Ariana, with the speed and precision of a military briefer, laid out the situation. Hermione had already contacted the other DA members, and instructed them to run interference with the children of Death Eaters in school, should they be seen spying or causing trouble. The mission required that the Death Eaters remain ignorant of any plans made to thwart them.
"Voldemort has planted a false vision in Harry's mind, showing the torture of Sirius Black," she began, her voice crisp and clear. "The objective is to lure Harry to the Department of Mysteries to retrieve a prophecy he believes pertains to them both. Our intelligence," she gave a slight nod to Harry, "suggests that a contingent of Death Eaters, likely including Bellatrix Lestrange, is already lying in wait in the Hall of Prophecy."
"It's a trap," McGonagall said, her voice tight with anger.
"Yes," Ariana confirmed. "A predictable one. And because it is predictable, we can reverse it. We will not be walking into their trap. We will be walking them into ours."
She moved to the center of the room, her presence commanding the full attention of everyone present, from the powerful Headmaster to the youngest Weasley.
"This will be a multi-layered, coordinated operation," she announced, her mind weaving the complex strategy into a clear, actionable plan. "Each group will have a specific role and a specific zone of engagement. Success depends on precise timing and adherence to the protocol."
She turned first to the student group. "Layer One: The Core Team. Harry and I will proceed alone into the Hall of Prophecy. Our objective is twofold. First, to retrieve the correct prophecy orb, which will serve as both the bait and a valuable piece of intelligence. Second, to draw the Death Eaters out and confirm their numbers and identities."
Harry's heart hammered, but he nodded, understanding his role. He was the lure.
"I will be responsible for Harry's immediate protection," Ariana continued, her gaze unwavering. "My priority is to keep him shielded and mobile. We will not engage in a prolonged duel. We will retrieve the objective and begin a tactical withdrawal, drawing the enemy after us."
She then looked at the rest of the D.A. members. "Layer Two: The Ambush Team. Ron, Hermione, Neville, Luna, and Ginny. You will not enter the Hall of Prophecy. You will take up concealed positions in the circular room that precedes it. The moment I give the signal—a silver Thunderbird flare—you will emerge and engage the pursuing Death Eaters from the flanks and rear. Your objective is not to defeat them, but to disorient, disable, and contain them, creating chaos in their ranks. They will notice you, but your training is solid, plus noticing students will cause them to underestimate our planning, thinking only school students are a part of it."
Ron, Neville, and Ginny looked both terrified and thrilled. Hermione was already mentally running through shield-penetrating hexes. Luna simply had a dreamy, determined look on her face.
Ariana's gaze then shifted to the professors. "Layer Three: The Heavy Support. While we are inside, the Order of the Phoenix, led by Sirius and Remus, will have infiltrated the Department of Mysteries and will be waiting in the surrounding chambers. They will form a secondary, more powerful cordon. As the Death Eaters are thrown into disarray by the D.A.'s ambush, the Order will strike, cutting off their retreat and engaging the most powerful opponents like Lestrange."
She was creating a kill box, a series of concentric traps designed to systematically dismantle the enemy force.
"Layer Four: The External Cordon," she said, her eyes now on Dumbledore. "While the battle is underway, Director Amelia Bones and a handpicked team of elite Aurors will have secured all exits from the Department of Mysteries into the main Ministry Atrium. Any Death Eater who manages to break through the Order's line will run directly into the arms of the law. There will be no escape."
Finally, she outlined the last stage. "Layer Five: The Final Net. You, Professor Dumbledore, and you, Professor McGonagall, will secure the Atrium itself. Your role is to handle any unforeseen contingencies—and to ensure that once the engagement is over, you can retrieve us and secure all Floo network exits from the Ministry, preventing any high-level political interference from individuals like Fudge."
It was a comprehensive, brilliantly layered strategy that accounted for every stage of the conflict, from the initial lure to the final, inescapable containment.
"And what of us, Miss Dumbledore?" Professor Flitwick chirped, his tiny face grim with determination.
"You and Professor Snape have the most critical role of all," Ariana said, turning to them. "You will remain here. You will secure Hogwarts. With the Headmaster and Deputy Headmistress absent, the castle is vulnerable. Your duty is to be its unbreachable defense, ensuring no secondary attack can take place while our forces are engaged elsewhere."
Snape, who had been listening with a dark, unreadable expression, gave a single, curt nod. He understood. His role was not on the front line, but as the guardian of the home front, a task suited to his skills and his complex position. This was also a safe bet for his spy identity.
"The plan is set," Ariana concluded, her gaze sweeping over the assembled group. "The communication will be handled via modified Patronus messages that will relay simple, prearranged signals: 'Engage,' 'Withdraw,' 'Target Secured.' Other than myself and Harry, the others will not travel to the Ministry by Floo, which can be monitored, but by a series of coordinated, short-range Apparitions directed by Professor Dumbledore."
She looked at each person, her expression one of absolute, unwavering resolve. "Voldemort believes he is luring a frightened boy into a simple trap. We will respond with the full, coordinated might of this room. We will not be the victims. We will be the hunters."
A grim, determined silence filled the office. They were no longer just a school. They were an army.
And they had just been given a battle plan, not from a seasoned general or a powerful Headmaster, but from a fifteen-year-old girl with a mind like a diamond and a will of forged steel. The Death Eaters in the Department of Mysteries were not waiting for a scared schoolboy. They were waiting for a storm, and they had absolutely no idea it was about to break right on top of them.