I've been messing around with Lesser Powers.

I noticed a while back that turning Night Eye into a Lesser Power makes it a toggle. So when you hit it again you turn it off. I was wondering if this is possible to do with other spell types?

Such as for example a spell I created called Celerity. What it does is blanket the character in the Ebony Cuirass shadow effect and then makes them really fast. It has a duration of 10seconds and it's a Lesser Power. But even though it's a Lesser Power it just resets the duration. How can I make it so that hitting it again turns off the speed increase and using it again turns it back on? So forth and so forth.