Bind the Heavens
This curse inflicts a months of drought upon an enemy's land. The magician paints a donkey's skull in gaudy colors, wedges papers bearing vituperative curses and the victim's name between its teeth, and throws it down a well - preferably the well of the victim. This offends the spirits of the land and water, who respond by steering the rain away from the victim's land.
System: Using a well that is not actually on the victim's land increases the ritual's difficulty by 2. If the ritual succeeds, however, no land owned by the victim receives any rain for one month per success rolled by the magician's player.