"Technically," William said, hesitating, "your potion did that." He took a few steps further in and moved around the edge of the room, wondering if he could block Gabe from seeing the hole blasted in the wall and encrusted with silver crystals. It was probably too late to hide the fact that the large wooden worktable was cracked in half, lying in two pieces on the floor and burnt halfway to ash.
He didn't even need to look at the ceiling; he remembered very well what they'd done to that. But they'd been desperate, and working on very little food and sleep, with undead House-elves roaming around the halls attacking and trying to eat people, and honestly William thought he should be cut a little slack.
"I don't know how easy you think it is for someone who never even made it through NEWT-level Potions to brew a complicated and volatile explosive mixture based on half-remembered instructions from more than a year ago," William said crossly, folding his arms stubbornly over his chest. "It's not, in case you were wondering. Particularly when the instructions in question tend to be more along the lines of 'wait for it to turn a sort of syrupy, golden-yellow colour that smells like nutmeg, you'll know it when you see it,' rather than anything clear and helpful. Not everyone knows that. Not everyone is a genius daredevil Potionsmaster with an aptitude for brewing brilliance."