Morrowind:Sound

	Sound
School		Illusion
Type		Offensive
Base Cost		3
Availability (Click on any item for details)
Spells Madstone of the Ahemmusa

Sound M points for D seconds

Creates a distracting noise in the mind of the target, decreasing their chance of successfully casting spells by M%.

[edit] Notes

Sound has a couple of advantages over Silence. Firstly, it always affects the target, whereas Silence can be resisted by Willpower, like Paralyze. Secondly, an enemy affected by Sound will still try to cast spells, meaning they'll waste their Magicka every time that they fail to cast them. An enemy affected by Silence, on the other hand, won't try to cast spells at all, and as soon as the Silence effect wears off they'll have plenty of Magicka to start casting them again immediately if the player hasn't had time to kill them.
Sound also has disadvantages compared to Silence. High strength Sound spells are not as Magicka-efficient as Silence spells, and unless the player uses an expensive 100% Sound spell, enemies will still have some chance of firing off dangerous spells at them.
Other methods of dealing with hostile spellcasters exist, and are usually more efficient in terms of Magicka. For example, Damage Magicka or Damage Intelligence are more direct. Of course, these assume the player character is skilled in Destruction. If they only have a decent ability in Illusion magic then this is neither here nor there.