In general, you cannot use Osiris scripting in Game Master mode. The reason is that when a Game Master mode savegame is loaded, all database facts from the savegame are deleted and the story is reinitialised from scratch. This was a conscious design decision of Game master Mode, because everything should be under direct control of the game master. You can use behaviour scripts, though.
Osiris tutorial videos from DOS1 (the language has changed a little, but the base concepts are still the same and these videos are still 99% relevant; you can ignore the last one about dialogs, as the dialog system has changed completely)
