Dangerous Forbidden Technique/Playing With

Basic Trope: Any attack, tactic, ect. that could come at a price (and very nearly always does). In other words, it is dangerous, and therefore forbidden.
 * Straight: Dave casts the Explosivo spell on a Boss in Mooks Clothing. Said spell causes the target to explode, but has a three-in-five chance of making the user do the same thing.
 * Exaggerated: …said spell could potentially cause an Earthshattering Kaboom if used incorrectly.
 * Downplayed: …said spell could cause mild burns to the face if the caster is too close to the target, making its use somewhat undesirable to begin with.
 * Justified: The target has crossed the Godzilla Threshold and the Explosivo spell, however dangerous it may be to the caster, the Boss in Mooks Clothing would cause a lot more damage if Dave didn’t use it.
 * Inverted: The Explosivo spell, although dangerous, is a staple of modern magical duels; therefore to not use it would be forbidden.
 * Subverted: Dave creates a magic shield around himself first to circumvent the possibility of blowing himself up.
 * Double Subverted: …but it turns out to be a bit more literal than that…
 * Parodied: The Explosivo spell has the unfortunate side-effect of possibly turning the caster into a bushel of daisies.
 * Deconstructed: Dave successfully destroys the Boss in Mooks Clothing with the Explosivo spell, but the rebound explosion that resulted severely burned Dave and killed off the rest of his party. He spends the rest of his life horribly disfigured and wondering if there were actually a better way to save the day.
 * Reconstructed: …however, Dave has since become a master of the Explosivo spell and is so profound at using it that he is able to blow up only his target and never himself or others.
 * Zig Zagged: The mentor who taught Dave the Explosivo spell inadvertently blows himself up later in the story, but Dave never blows up.
 * Averted: The nature of the Explosivo spell dictates that only the target is at risk of exploding, never the caster.
 * Enforced: The writers are trying to set up a Forbidden Chekhov's Gun.
 * Or prove that Anyone Can Die.
 * Lampshaded: "Dave, are you crazy? You could have blown up that brute and yourself at the same time! There’s a reason that spell was outlawed, you know!"
 * Invoked / Exploited: Dave tells Emperor Evulz how to use the Explosivo spell, and then reveals to him that Evulz’s Dragon failed to recover the MacGuffin. Evulz decides to test out the Explosivo spell by testing it out on the Dragon. Both of them explode when the spell rebounds, which means that Dave saved the day without actually using the Dangerous Forbidden Technique in the first place.
 * Defied: Only a novice could possibly blow himself up, and so the Explosivo spell is only taught to advanced mages. Dave is one such mage, and thus is incapable of accidentally killing himself.
 * Discussed: “Why the heck would I use that spell?” “You shouldn’t, Dave! That’s the point!”
 * Conversed: “How much you wanna bet he’s gonna use the Explosivo spell at some point?”

The Dangerous Forbidden Technique trope is so dangerous even its trope page is forbidden.