OzoneSherrif said:

Instead of another technological terror super weapon maybe it should have been some devastating dark force attack the Emperor was cooking up. We could have finally seen a demonstration of how the power of the Force is actually stronger than the ability to destroy planet.

i dunno... how about something as simple as the Emperor waving his hand and several Rebel ships getting obliterated?

I like the idea of having the Emperor do something that shows how powerful the force can be, but not so much this idea specifically. I like the idea of the force being tightly knit with living things. Sure it can move inanimate objects via telepathy, but that's not where the real power lies. The real power lies in the ways it can be used to monipulate or overcome other people (like the mind trick).

But taking your basic idea in another direction... I'd borrow the idea someone else had where the rebels are led into a trap, thinking they're going to wipe out the empire once & for all in a big battle on and over the capital planet. But during the battle, the emperor uses the force to manipulate the rebels & maybe incapacitate them. I'm invisioning something like what happens when Professor X targets all the humans via Cerebro in Xmen 2.... In the heat of battle, suddenly huge chunks (or maybe all) of the rebel forces are unable to fight due to mental interference, extreme pain, hallucinations, or something (or maybe all of the above?). This could serve dual purposes too. First to show the true power of the darkside, and secondly to act as the trigger the breaks Luke's resolve so that he gives into his anger and first strikes out against the emperor (which would then lead into the duel with Vader, just like in the film).