"What do you mean the vault is empty?!"
"Just that, sir. It's empty."
"There was a half tonne of gold coins in there! Did you see a cart? Any orcs or ogres? A dragon?! It's not like it just got up and walked away!"
What if casting magic changed (for a few hours or days depending on the strength of the spell) the colour of the skin of the spellcaster? It could lead sadly to a very racist world to rp in.