Sticking strictly to the OP requirement of handheld items that can be teleported into someone, I think playing cards is a good starting point, but save the ordinary cards for mundane opponents. The existence of one superhuman implies there could be others. If the teleporter exists in such a world, I would suggest not simple playing cards for those enemies, but tarot cards. And not just any tarot cards, but tarot cards with the faces of your enemies on them, like these, so you can monologue about their fates before killing them with their own card.
With ample preparation time, you could have your sorcerer buddy enchant the cards so they count as a magical attack on someone vulnerable to such things, or dope them with troublesome substances like kryptonite in Superman’s card or graphite whiskers to short out Vision or Iron Man’s armor.
I think for a comedy slant you might want to go with something shaped like a classic Valentine’s Day heart (hard plastic, fist-sized) and maybe inscribe each one with a little love note. Transport one of those into someone’s chest in place of their actual heart, and then fall down laughing every time you imagine what it would be like to be there for the autopsy.
If you can teleport chunks out of a person at range, what is stopping you from just teleporting the left half of their body two feet further to the left? If the character is for an RPG, that may be too game-breaking and over-the-top. For a horror novel antagonist, it might be perfect.
The OP specifications put some limitations on it, which can be more fun when you have to come up with creative ways to work within those limits. You can’t teleport it if you can’t touch it. You might want your “ammo” to be nonmetallic and unobtrusive, so you can walk into a bank or prison with it, etc.
I like the Valentine’s Day heart thing. That has some psychotic style to it.
How does your teleporter work when there’s already something at the destination? Do they overlap, with densities adding? Is the previous thing displaced, and if so, in what direction? Is it like the new object is coming through a portal, or expanding from a point? Or is the matter in the destination location transported back to where the object came from, a swap?
Have a stack of cards, all the 3 of Clubs. On each one write “Is this your card?” Then teleport them into peoples brains. Let Penn Jillette take the flak.
Use one of those sponges that have been squashed down and put inside of a capsule…the kind you give to kids to drop into the bathtub and watch it grow. It would do the same thing inside the body. And they’re small and light enough to carry a lot of them.
The object appears and completely replaces where it reappears. If you teleported a marble inside a glass of water, took the marble out and weighed the water you would find a marble sized amount of water is gone entirely.
If that’s the case, the most efficient procedure would seem to be to use lumps of polystyrene or something else very light and easy to carry. Teleporting them into someone’s brainstem or heart would be equivalent to teleporting out a similar-sized lump of tissue.
You people have no style. I mean, sure, if you want to be ruthlessly practical, like some kind of military special forces, then sure, go with the lumps of polystyrene. But then be prepared to be regarded as a common criminal, a nobody. If you want to be a super-villain, or a super-antihero, you need to have a little fun with it. “Best” doesn’t just mean most efficient: you also need to think about branding. You want to strike fear into the hearts of your enemies? What better way to do it than by replacing their literal heart with one of your own?
For those occasions in which you only want to disable, humiliate, or threaten someone (maybe you need a hostage?) squish a packet of Taco Bell diablo sauce and zing it up their sinuses, pop ice shavings into their ear canal, and bamf a dust bunny into their esophagus. Making Wolverine hack up a hairball or giving goody-two-shoes Superman a lungful of weed smoke would be hilarious.
What sort of liquids turn into gases above room temperature but below body temperature? (I know of gallium, a solid that melts at around 30 degrees.) The massive expansion in volume could cause a stylish explosion! It could also result in a slow expansion (so the teleporter is safely away before it goes bang!).
Or maybe just insert people with something like a spring (that expands once inside the human body and no longer constrained).
We could go biological. I read a horror novel where people could be implanted by masses of spiders. Yuuuucck! I’m not scared of spiders, but I would definitely be scared of those spiders!
It occurs to me: Are you planning on using this device against superhumans? Some of them are aliens, or robots, or otherwise have a nonstandard anatomy, physiology, or metabolism. It’s tough to teleport away someone’s heart if they don’t have one to begin with. You’re going to want a variety of options, for when your signature method doesn’t work…
Teleport the person inside a rock formation or middle of a lake.
Items you could carry as weapons? Magnets. Teleport them inside your enemies stomachs. They wouldn’t live long. (kids swallowing magnets is already a real life medical emergency)
They missed one that’s incredibly absurd, from back in the 1960s. He once used his ring to make a giant fist and a giant cocked hat, just so he could “knock they guy into a cocked hat”.
If you’re going for stealth assasination, take a suppository (or 2) and beam them into the heart or brain, or the aorta. Quick death, and then it melts. the residue would be detectable, I suppose, but only if they knew to look for it.
