Weaken

Weaken is a curse-type combat spell available at level 11 Magic. It costs 3 water, 2 earth, and 1 body rune to use, and yields 42 experience when cast successfully. If cast unsuccessfully, like all other spells, you will be unable to cast any spell for 20 seconds.

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