When an opposing army brings in the big weapons, your kingdom has no choice but to ante up or fold - and a trained Battle Mage from the Guild of Arcane Combatants if nothing if not a big weapon. But what happens your generals and their generals have a common goal?
A wizard has cast a slow action freezing spell upon a PC. The air gets colder around the PC by one degree a day. If the spell is not broken within a few weeks the PC will freeze and die.