"Are you sure you've identified the right spell represented by each of the urns? I'm not a magician, so I'm happy to defer to your expertise here, but if there are two that are meant to be left out I think it's worth being reasonably sure we don't include them through simple oversight. Maybe two of them don't match any known spell, but our imaginations make links because we want to find them."
"Perhaps if you take us through them and set out your reasoning... any that are uncertain might emerge?"