This is a good basic primer on the weave:

https://forgottenrealms.fandom.com/wiki/Weave

For more on its history, why you don't mess with it, and why spells are capped at ninth level (with very few exceptions):

https://forgottenrealms.fandom.com/wiki/Mystra (The goddess in charge of the weave)
https://forgottenrealms.fandom.com/wiki/Karsus (The man who used the only twelfth level spell to wrest control of the weave from Mystra, and succeeded...for five minutes. No prizes for guessing what happened next)
https://forgottenrealms.fandom.com/wiki/Helm (A god who killed Mystra once, badly damaging the weave and creating wild magic and dead magic zones, lovingly known as Helmlands. I hope we encounter a few of those in our adventures, if only to make things more interesting)

Lover of non-haughty elves and non-smutty lesbian romance
"1404. I will not spoil the adventure's mandatory ambush by using the cheesy tactic of a "scout"." - From "Things Mr. Welch is no longer allowed to do in a (tabletop) RPG"