Have you noticed how hard it is to instill actual fear in players? Sure, you can magically "fear" the PC, but how do you get the player emotionally invested into his character's danger?
As a rule of thumb, it's time sensitive, and the longer the time, the more fear (or suspense) it generates.
Here's how it works. PCs risk death constantly. The threats are immediate, and success or failure is determined fairly quickly. There is little, if any, fear or suspense, generated.
You need a long term threat with a due date of sorts. A curse or disease that will run it's course in a certain time frame before ending in the PC's death unless a cure is found works pretty well for this. Even a word of potential execution by a political heavy or a guild leader if the PC's can't accomplish a certain goal in the allotted time frame can do wonders.
The secret is giving the PCs (and in turn, their players) the time to think about the price of failure. The suspense itself adds to fear, or the illusion of it.
How do you generate fear in your games?
The Atlas of Pern -
1 hour ago