Why would a human bomb not be blown apart by rune magic?

Question

I am a homicide detective on the magical police force. Runes are magical symbols fused into objects that imbue those items with magical power. These spells are stored in these runes for long term use to provide immediate access. Runes generate large amounts of heat when they are activated, which is why they are are usually placed on items and not on the skin. However, a horrific use has been found that evil mages use to there advantage.

Evil mages have been using innocent people as human bombers to hit specific targets, do damage to approaching armies, or simply to send a message. A special rune is magically fused to the skin which the witch is mentally attached to. The witch can then control the individuals movements, leaving them aware with the mages controlling them from a distance. At the mages will, the rune activates, turning the person into a human bomb. The explosion vaporizes the area closest to them, and anyone caught in the blast is blown to pieces.

There is however something strange about how the rune operates. When normal suicide bombers activate their explosion, their own body also suffers damage and is blown apart, leaving little to clean up by the authorities. In this case, the body is burned to a crisp, but remains intact. The charred corpse remains in one piece, with everything else either vaporized or destroyed.

When a bomb explodes,the force of the explosion travels outward, destroying everything in the vicinity with the victim at the center of it suffering the most damage. This rune works differently, destroying the surroundings while leaving the body itself intact, albeit burnt to a crisp. I need to explain how the force of this bomb would propagate away from the victim without damaging the remains themselves.

Answer 1

The corpse is a conduit for the magic.

Basically, the way the magic of the rune works is that it gets channeled through the user, and the frame is magically reinforced as a result. Imagine the suicide bomber not only as a carrier for the explosive, but also the conduit for it - like a red hot heating coil. That way, the person gets charred to a crisp, but suffers no damage aside from it.

Answer 2

It's designed that way to protect the rune.

Your evil mage did a lot of experimentation before they perfected their bomb. In the first few trials, the explosion would utterly destroy the body, but the fireball would only extend a feet away in every direction. Too small for the mage's purposes. The reason: the rune fuels the explosion as it's happening, and if it's destroyed in the blast, the energy source is cut off. The solution: the mage reworks the magic so it protects the skin surface where it's printed.

The mage's latest design creates a thin boundary around the skin in the fraction of a second before the blast goes off. The host inside dies instantly from the force crushing their every bone, but the barrier keeps the general shape - and, more importantly, the rune itself - intact. After the pressure wave disperses, the barrier lifts, the body is charred by the remaining heat, and what remains is a blackened, but still whole, corpse.

Answer 3

The explosion is a vector force away from the body in all directions.

Force emanates strictly away from the body carrying the rune. Because the air is entrained in the force the movement of air is entirely away from the body. There is heating of the air, converting it to flame, and therefore some radiant heating effects the body but no convection because all air is moving away.

The carrier of the rune is slightly charred but usually dies because of explosive decompression: as air moves away in all directions the air pressure at the center of the explosion drops precipitously.

Answer 4

The Bomb Rune is not tied to the puppet

The thing about the standard Self-Bomb runic array is that they go out with a bang. As such, the bomb rune is tied to themselves in some way and the rune is designed to use that connections to provide extra fuel to create a bigger bang. By violently consuming the carrier, more fuel is generated and you get a bigger boom. Coincidently, it also neatly disposes of the bomber by energetically partitioning and relocating the caster to a myriad of quasirandom locations at an accelerated rate of travel.

However, this sort of connection to a person has to be voluntary to work properly.

Enter the Puppet Bomb runic cluster (or just rune). Realistically, it does three jobs: Allows remote control of the now human puppet, protects the victim until detonation, and makes a big boom when activated. The first and the third are obvious, but the second function is there in order to protect the puppet from the heat generated by the rune in the first place.

When the explosion aspect of the rune is activated, the containment part that was protecting the host is consumed, that energy also going into the explosion's power. Without the containment aspect, the heat from the runes and the flaming explosion after cooks the puppet swiftly. If that did not do them in then the explosion ceratinly would. However, unlike the standard bomb-type explosion, this is closer to a Hollywood explosion with more fire than boom. It's still nasty and lethal to those within the blast radius, but it is not bad enough to ... aggressively relocate the puppet to multiple locations.

Answer 5

The first rune creates a strong force field just below the skin of the target when triggered. The second rune, triggered just after the field is ready, triggers an implosion field around the target. That implosion is very fast, very strong, and compress the air a lot, turning into a hot plasma. Said plasma will hit the force field just below the skin, the heat will shatter all the molecules above the shield, releasing a lot of energy in the process, and blowing everything around. Depending how fast the compression is you may instead fuse some hydrogen atoms to get very high yields, like 1T.

Why don't the wizard place the force field in center of gravity of the body and get more bang for the buck? Because the force field vector that resists the implosion is normal to the force field rune and the wizard can't etch the runes in the target's spine, must be just below skin, like a tattoo.