When Albus Dumbledore tried to use legilemency on Edward Elric to ensnare the boy's mind he was in for a nasty surprise. The boy's mind was protected, hidden behind a large pair of stone doors in empty space. There was a white on white silhouette, with no features, sitting in front of said doors. Clearly, Dumbledore reasoned, this was the boy's mental defenses, and very clever they were too, although hiding behind an obvious gate was ineffective, when all one had to do was open it. Although the white shape might be meant to be a guard. He approached the doors and pushed. Nothing. Ah well, perhaps if he went around them. He tried. Nothing happened.
"You cannot enter. You haven't paid the toll."
The old wizard would deny jumping upon hearing that legion-like voice, but jump he did. The white shape had stood, and a grin had appeared on the white head.
"This boy is Mine, and you will pay for this trespass. For attempting to gain access to the True Knowledge, bypassing the Equivalence of the world, and for attempted enslavement of one of mine, you are denied what you desire. You will never know if your plans succeed or fail. You will die before they can come to fruition, Mis-ter Wiz-zard. "
This was no mental guardian! Trying to squelch the beginnings of fear, he asked it, "Who are you?"
"Who am I? I'm so glad you asked. One name you might have for me is the World. Or the Universe. Or perhaps God, or perhaps The Truth. I am all, and I am one. Which of course means that I am also, You.
The Gates opened, and the old wizard tried to withdraw from the boy's mind. He did not want to see what was on the other side. "Oh no you don't. I am the Truth of your arrogance, the inescapable price of your deceit. And now, I shall extract from you the price you must pay." The wizard was effortlessly lifted by the white shape, and drop-kicked into the Gate.
He struggled uselessly as the hands dragged him into the Gate, and the eye within it. The doors slammed shut. He was pulled through the blackness and could feel himself disintegrating, as it felt like his mind was being scrubbed out, scoured clean. Then there was a jerk and he was back in his body, in his office, and feeling pain explode in his newly broken nose. There was a clap, blue light filled the room, the boy slammed his hands on the ground, and everything in his office became a coil of material wrapping around him and fusing with the wall. His desk, everything on it, the devices linked to the wards at Privet Drive, all went into binding him securely to the wall.
"Try to trap me will you, you old bastard!" The Elric boy spat, picking up the Elder wand from where it had fallen. "You wizards seem so attached to your sticks. I wonder how much you can do without one." He snapped it. "And that Harry kid you were planning to use and left in an abusive home, well he won't be staying there. Al and I will take better care of him than you." He marched out the door, leaving Dumbledore hanging there, reeling over the fact that the Elder Wand, the Deathstick, the most powerful wand in the world, crafted by Death, had been snapped. He didn't even wonder how the Elric boy had done what he'd done to the office. Yet.
"I told you this was a bad idea," said the Sorting Hat. "Even if you as the head of the school are only obliged to listen to my advice, not do what I say, I told you that trying to mind scan an alchemist was a bad idea."