The benefit of being inside the castle was that he didn't have to worry about the sparks the dummies were shooting. He was protected by the walls. The downside was that he didn't always have a clear range. He had to aim through windows or something. When that older girl whose name he did not remember joined him in the castle, Olly waved and grinned at her before turning his focus back on the fight.

If he could position himself to be able to shoot over the top of the castle, that seemed ideal. So he placed on foot onto a window and lifted himself up so he was at a might higher vantage point. It was easier to see all the dummies. There was one pointing their wands toward the castle. Oliver aimed his wand at it.

"Expelliarmus!" Wish a swish and slick of his wand, the blue jet of the spell was shooting toward the dummy. As it met its mark, the dummy's (fake?) wand flew out of its hand.