Curse

Curse is a curse-type combat spell available at level 19 Magic. It costs 2 water, 3 earth, and 1 body rune to use, and yields 58 experience when cast successfully. If cast unsuccessfully, like all other spells, you will be unable to cast any spell for 20 seconds.

Curse has the effect of temporarily decreasing your opponent's Defense level by up to 5%. However, the spell cannot be cast on the target if their Defense is already reduced, even slightly. As a result, the player cannot use both Curse and Vulnerability on the opponent to stack the Defense stat reduction.