Never used ’em.

Special Action key? What is that?

The "F" key just central your camera.

The F key is for Special Action, which is only for a certain section, the tournament arena.

If you want to give up, you press F.

Oh, that’s what it does. No wonder I didn’t know what it does since I’d rather die than yield ;p

I think Lures are very useful as decoys.
To give an example.
Many people have trouble with the Nekker nests that are outside of Flotsam. Nekkers are indeed annoying in how they can swarm you, and have some very quick and nasty attacks.

So how can you make sure you don't have to deal with such a swarm. Simple, by luring them away to another location.
Before you are going to deal with a nest, put up a few lures on a place some distance away.
The nekkers will be drawn to them, leaving their nests unguarded.
Simple as that !