Lots of good info here about using them. I'll just add that I've found it incredibly useful to make them both macros that announce both to the raid and the group that I'm casting them.
The wizards were bad about casting fusion just as I'd torpored the tank, and since we have no coecers or dirges or assassins or swashy hehe agro control is tough sometimes. And torpor followed by fusion was a bad day for the wizard who did it.
Since we walk a fine line with the agro, we have an over zealous monk that is actually the usual recepient of my torpor. Reminds her to back off and that she isn't the MT.
All of our healers announce when they do their stun heals. It works out well for the rest of us.