Sneaky bastards, the lot of them
Some sovereigns prefer a different sort of tax from their subjects - whether freely given, or taken by force.
A dreamer is one who can only find his way by moonlight, and his punishment is that he sees the dawn before the rest of the world
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.