[quote=@Zugzwang]If souls exist in this game, what do they do? What functions does not having a soul prohibit, and what function that we think are done by the brain are actually done by the soul? In addition, how does the soul interact with reality, and how can it be observed? If I created a perfect copy of a living brain and put it in a perfect copy of the corresponding body, what would be the result? What is the soul made of? Do souls significantly vary? Where are they stored in the body, or where are they physically when attached to a thing?[/quote]

Souls aren't a very scientifically solid concept. Like everything else here, they're a gameplay mechanic, a resource. They develop in the brain of their original bearer, but once they're severed from the mortal by magic or death, they can take on the same functions by themselves, without needing the physical infrastructure of a brain but still needing some kind of host entity (if you're cruel, you can give eyes to a rock and plant a soul in it to watch it suffer in boredom for the next million years). A mortal with their soul removed, or one created without a soul, has a brain, but won't use it- They'll die or go comatose. It can only be interacted with by magical means, and until severed, it occupies no space and can only be sort of sensed by a god- Not seen or heard or smelt. Once they're severed they just sort of sit around like a bubble or cumulus cloud or pile of translucent goop, small enough to be picked up with both hands but pretty amorphous. They dissipate unpredictably when not in a host, disappearing suddenly after anything from a few minutes to a few hours, but can be sustained by a god (pickled, as it were) to last longer.

[quote=@Zugzwang]Speaking of pair production, how hard would it be for a deity to make some antimatter? I would figure if we can make a skyscraper in an hour or two, we could make a pile of protons with their chirality swapped over without too much difficulty, if we really wanted to fuck everything up. Even excepting antimatter, though, I know you say we can create an explosion, but it seems like it would be much more time-efficient to just make a skyscraper of tnt, or your regional equivalent, and light a match.[/quote]

You could try that, but the process of producing something with that much potential to destroy complexity would trip off every other god's Bai Suzhen Sense, also known as their ohfuckometer, whether they're nearby or in the mortal plane or not.