There are no scrolls in this world, but there are crystals of various sizes, colors and qualities. Every spell has a requirement on the amount and characteristics of crystals that must be held in order for the spell to be cast, crystals which would shatter should the cast be successful. Now picture a land where crystals are scarce except for high concentrations of them in specific spots throughout the land. A number of scenarios could occur, such as benign companies selling the mined valuable for cheap, a region in constant magic-intense war zone, an area of crystals in the quicksand, or an undiscovered patch next to a town...
A revolt or attack happens against a strong city/kingdom. All the losers of the battle that can be captured are brutally crucified along the roads that enter the kingdom to show their strength and as a demonstration of what happens to their enemies.