OK, here's what I ended up posting:

"Have sseveral ssecretss you would consider worth a hosstage, but before that, ssusspect your plan to get rid of me flawed. Am Tom Riddle. Might have accesss to horcruxes. Unlesss grant ssecurity of parentss firsst, will raise wand at minionss; they will casst avada kedavra, sskipping sseveral of your intended ssteps; am gambling on returning from horcrux before you hurt hosstages."

Nonplussed, Lord Voldemort gestured to his Death-Eaters. "A small change in orders, gentlemen. If the boy speaks in human tongue, makes a sudden move, or raises his wand away from the floor, don't case avada kedavra on him - cast stupefy inst-"

Before Voldemort could finish his sentence, before the Death-Eaters could switch mental tracks, Harry's wand - which had never stopped pointing at the floor - finished casting the partial transfiguration. A very thin section of the floor, in a circle surrounding Harry, was now sand. The younger Tom Riddle, along with the piece of floor he had been standing on, quickly fell to the ground below, away from the Death-Eaters' line of sight.