The big question though is how much of the foam goes poof per 'kill.' You ever read any of the Dresden Files books? In them, one of Harry Dresden's favorite ways of mystical eaves dropping was to use sympathetic magic on a can of silly string. Put silly string on an object, like one of the carts hotels use to move stuff when you order room service, and spray some in his own ear, and the magic lets him hear what the string in the room 'hears' regardless of distance, but the magic only works because the foam all came from the same can.
So when Taylor kills some containment foam that has been sprayed at her, would she kill just that chunk of foam, or would she also kill the unused foam still in the sprayer because the spray and the reserves are conceptually one thing? And if she can kill the unspent reserves, how far back does the conceptual chain go? The regional level, letting her destroy BB's entire stock of foam with one swing? The industrial level, letting her kill entire production runs by the simple expedient that the whole batch was conceptually one object when first mixed up?
Because, if I'm understanding the BS that is the MEoDP correctly, by internalizing the concept that 'Words can Die,' Taylor can, in theory, murder languages with a knife swipe. Which means, in theory, that Taylor can similarly internalize that containment foam can die, and kill the entire concept of the stuff by stabbing a small sample. And we all know that accidently murdering the PRT's primary method of non-lethal take downs is the sort of thing Taylor would do.
To be fair, i was trying to simplify when i said 'concept', but thats not quite right.
Assuming Ryougi's version of the ability (which is the more powerful one) she can kill anything that A) is connected to the Root (which is basically everything below a certain class of lovecraftian scale cosmic entities). B) Will ever end in any sense of the term, if it will die, disintegrate, be forgotten, and/or fail or any variation on these she can bring that about immediately. C) has a shape and nature she can understand as being able to 'end.
For example, there is no mechanical reason she cant 'kill' a dead tree, but Ryougi generally considers that to be dead already and so she cant see the lines like she can on a living tree. By a similar filter, she cant kill all trees by stabbing one tree, because shed need to have a particular object that is both literally connected to the Root of all trees, and that she can comprehend as being all trees at once, and as something she can kill. (No, this does not extend to zombies, which are ambulatory and understood as being 'alive' in a sense, just not the technical one, so she can still kill those. Along with ghosts, spirits and the like)
Furthermore, as i implied above, this ability depends on her ability to see the lines. But the more abstract a concept is, or the more perfect the existence of her target, the harder the lines are to see. For example she fights a McEvil Wizard at one point who 'stopped' his existence, whos Origin was Stillness and who had a magical juju thing that should have made him basically immortal. She did manage to shank his ass eventually though by finding the line between him and the Root and severing that, but not before he wiped the floor with her extensively. She also took a very long time to learn to 'see' another character's space-warping 'twist' ability because it was basically shapeless, and couldnt cut a third character's precognition ability until she understood how it worked (which is to say, he was imagining a future he wanted, and acting to being it about, meaning there was something for her to cut... the future he desired.)
In more simple terms, she kills specific instances of concepts, not the big idea concepts that they are based on, because those sorts of things generally dont come in a easily comprehensible form that can die.
That said all the above limitations only apply to normal Ryougi Shiki/SHIKI, and not
⸢ ⸥ which thinks all those limitations are adorable and is capable of much greater degrees of comprehension than any mere human.
A contrasting example is Touko Shiki, who being a different person has different ideas about death and the functioning of his eyes, so his powers work slightly differently. This is aside from the fact that he didnt get Gaia as a external processor the way Ryougi did and so is way weaker in general.
Here is a good example of the power in action against a tricky opponent;
