I admit that I have experimented with the finger chopper (Hades) that has a real element of danger. The effect has two safeguard checks and while it probably can't actually chop someone's finger off in the event of a mistake, it can cause a nasty gouge. For this reason, I don't perform it.
For me, it's the tricks that I perform all of the time that I tend to make mistakes with because I get too comfortable and can ultimately get careless.
"Shiv" Putting spectators in danger came to mind recently when I was looking at Andrew Mayne's "Stain-Shiv," a DVD that teaches two tricks.
The first, "Stain," involves the revelation of a word or image on a card that is placed in a plastic bag that's filled with an unidentifiable fluid (blood?). The method for the word revelation seemed entirely too obvious to me but the appearance of a mysterious image (your choice) has potential.
The second trick, "Shiv," is a Russian Roulette style routine where you insert a sharp pencil into an envelope and mix this sealed envelope with others that have drinking straws in them. After mixing the envelopes, the spectator freely selects envelopes and then stabs them into his or her body.
At the end, it's the envelope with the sharp pencil that somehow remains. This is a plot that Mayne previously explored on his Maynia DVD with a routine called "Stab'd." You can see both "Stain" and "Shiv" on Mayne's promo video.
While "Shiv" and other effects sound safe on paper, I think that it's all too easy to make a mistake. I know that in performances I've forced wrong cards (I succeeded with the force - I simply forced a card for another trick). And numerous other things have gone wrong.
Tension Admittedly, the emotion of tension and apprehension is one that magicians don't often create. But I think that if it's anyone who could potentially be injured during an effect, it should only be us, the magicians.
Furthermore, I don't think it's right for a magician to put a spectator in peril - real danger or not - to entertain everyone else at that spectator's expense. I've witnessed hand chopper routines where female spectators were nearly in tears. This isn't entertainment and it simply promotes bad feelings towards magicians who exploit their positions of power.
As a cardinal rule that's up there with not divulging secrets, let's keep danger away from our spectators.