So, the Pandora's Box contains a trigger for an event (you click on the box twice, and a window appears for entering the event name). You give it a name, for example, "Artifact." Then, click Campaign -> Campaign Properties -> Events -> Local Events -> New. And enter the event name, in our case, "Artifact." Then, on the Script tab, click New and choose an action. For example, choose "Show Message" and enter any text. Then, below the text, there's a window labeled "New." Click it and choose "Give Artifact" and select something. After all these operations, click "New" again and "Remove Script" if you want this event to happen only once. Then, click OK everywhere, and that's it;) Here's an example I've uploaded.