Headaches are an annoying and uncomfortable experience. But migraines are much worse. Although it does not occur to everyone, those who suffer from it usually describe it as a throbbing pain that limits their actions. It's often accompanied by nausea, vomiting, and extreme sensitivity to light and sound.
In this world, fighters use a variety of weapons to defeat their enemies. Knowing the effects of migraines, a few powerless clerics cornered a local wizard, threatened his life, and commanded him to create a spell that would cause a migraine in someone else. The sorcerer, with nowhere to retreat, created the spell but restricted it so that it could not be cast on those who could not defend themselves from it. The spell has been known as the Induced Migraine since then.
It is one of the most debilitating spells in the cleric's arsenal. By inducing excruciating pain in their enemies, they can effectively disable them and render them unable to fight. It can be induced only to spellcasters.
While the pain is temporary and can be removed, it can still be incredibly debilitating for those who are caught in its grasp.