Artifact generation.

I wondered how this could be and tested a bold hypothesis. In short, the contents of the chests depend on the day they are accessed and the order in which the contents are taken in one turn. If two chests with artifacts are taken simultaneously, the order in which they are accessed directly affects what each one will contain. It is not possible to obtain exceptionally rare artifacts in this way, but it is quite possible, and even useful, to get +2 Knowledge instead of +2 Attack or +1 Damage and summoning elementals.