"Take the gloves off," Snape snarled, stepping back into the shadows. Draco Malfoy saw ... Harry Potter appear in the light mist in front of him.
Harry hollered, "Expe-"
Draco elected not to listen to the rest of that, rolling his way out of the line of the spell. Not seeing any cover, Draco started making some, transfiguring rocks and bushes out of the ground beneath them.
Potter wasn't trying to hide, he was casting, over and over again - cutting curse, Bombarda (that hurt, the rocks exploded, sending rocky shrapnel into Draco's leg).
Behind a rock, Draco cast the stinging hex, watching Potter dodge.
"Is that all you got, Drakey-boy?" 'Potter' called, and Draco Malfoy rapidly started to reevaluate. This clearly wasn't Potter, he wasn't clever enough to come up with that nickname, and wouldn't bother using a nickname someone else had come up with.
"Flippendo," Draco Malfoy tried, and then, in a split second, transfigured two mirrors flanking 'Potter'.
"Avada Kedavra," Draco Malfoy cast, the green curse rebounding from one mirror to the other, hitting Potter on the third bounce, when he was in the middle of jousting with Malfoy about his lack of aim.
"Well done," Snape said softly, and Draco wondered if he'd imagined the cast of disappointment on his face. Probably not. He'd known Snape since he was very young, after all.
[a/n: Draco knows to take Snape's orders seriously. That doesn't mean he doesn't still play with his enemies, that's testing them to see what they're like. Slytherins like finding flaws - Malfoy had several ways to take this thing down; he just chose the quickest.