Luka himself is taken aback by the size of it. "Uh, sure, help yourself."

He realizes this offer might have been a mistake as it is likely to disappear more quickly than he'd bargained for.

"So I used magic they were trying to use to reach to... to kill them?" It doesn't sound very good put to words like that. But he had no idea it was coming from them. He thought it was meant to help him this whole time.