The guards at the entrance gate of Canterlot Castle crossed their spears to block the grey Unicorn's way as he advanced on them. "Halt!" they exclaimed, clanking their spears to reinforce the idea that he shouldn't be crossing them. "What business have you in the castle?" He ignores them and keeps walking. "Answer!" they shout at him, the Unicorn guard calling up a wall of magic, which the advancing Unicorn calmly passes through. The guards gasp and lunge at him, attempting to restrain him. Somehow their attempt falls short and they fall to the ground. How could they miss such a slow moving pony?
"Secure the gate!!" they call through, trying again and failing to restrain the advancing Unicorn. Another pair of guards arrive as the portcullis closes behind them, brandishing their spears. The advancing Unicorn ignores them, too, and the four jump at him, somehow completely missing him entirely and colliding with each other in midair. They fall into a tangled heap on the ground, getting back up just in time to see him pass straight through the portcullis and be accosted again by the guards behind, with the same basic results. The alarm is sounded and more of the guard mustered, a full panic taking the castle and the seemingly unstoppable pony making his way through.
All their efforts are for naught, as he keeps advancing inexorably around or through every barrier in his way until he reaches the balcony from which the princesses customarily address their subjects. He clears his throat, the sound magnified throughout the city, and a great hush falls over it as they wait for whatever was coming. After a long moment of silence, he speaks in a low rumble.
"Please be quiet. I've been trying to sleep."