Paralyze is an Illusion effect that causes the target to be unable to move or take any action including attacking, blocking, or using objects. The magnitude of the effect is the duration. Paralyze effects, besides invisibility, are among the most costly in the school of Illusion magic, so a very high skill level will be required to make this spell efficient and cost-effective. A useful side effect of Paralyze is that you can pickpocket the enemy NPC with 100% success, no matter your sneak skill. You don't even need to have sneak active, just target them and press the activate key. This comes in handy when fighting enemies who have a lot of healing potions, as you can steal them, making the enemy much easier to kill.