[StevenH]

Re: spells available in different areas of Yrth....

Let's introduce something I call "Ethnothaumatololgy". That is, the collection of spells that a culture has access to. In other words, their spell list. Each different group/culture will likely have different spell lists, or, if using "basic magic", which spells are available to learn in that culture. Gate spells may never have even been developed.

For a world I built (and never got a chance to run, dammit) I went through with the prerequisite charts and figured out which spells each culture had, based upon their needs and requirements.

A culture will only really use what works for them (not including edge cases and outliers). So the spells they teach their mages will not (under most circumstances) be the full spell list. A culture whose settlements are all high up in the mountains may not have discovered/figured out any spells related to the ocean. An underwater species won't typically develop fire spells, because fire doesn't work underwater. It's not a tool in their tool box.

So Megalos will have one set of spells, Caithness another (likely severely truncated, since they live in a low mana zone*), and al-Wazif yet another. Everyone has different priorities, although there will obviously be a lot of common spells and overlapping uses.

* Which also implies that since magic is less reliable, they will likely focus on other means of solving problems. Means that will be reliable anywhere. (And I always considered their low mana zone to be their best defense, especially against Megalos and their reliance on magic.)