Hi Cromcrom,

The DOS1 video series on Osiris scripting is still a nice introduction to the syntax and overall scope of story scripting. You can ignore the dialogue related one for now as the dialogue editor is pretty different (although you can still create scripts for it similar to the ones you see in the tutorial).

There is also quite a bit of good information on the wiki about Osiris:
Osiris on the Larian Wiki

Osiris is essentially an event driven model. When you create story scripts, you basically inform Osiris of the kind of events you want to be notified about, and then take some course of action. So you can catch an event like, anytime someone uses item X, anytime something gets added to a character's inventory, etc, and then perform certain actions which may themselves trigger additional events. There are a lot of different options really.

You can create procedures in Osiris. They are kind of like inline functions.

DOS2 Mods: Happily Emmie After and The Noisy Crypt

Steam Workshop
Nexus Mods