I thought the ability to create runes was simply taking a sort of magic-sponge (essence) to a place where a certain kind of magic overflowed (altar) and it was temporarily capturing that power to be released later as magic. The Stone of Jas (SOJ) however if I understand is the root of this magic, so if simple rocks by being near the SOJ became magic sponges, why couldn't we the player receive some sort of additional tendency with magic? Granted the Moonclan had more time to be around it hence their more magical state, but any player that has been in contact with the stone should theoretically have a marked improvement in magical ability (not just a paltry XP reward, some sort of tangible, real effect like SOL's rune saving effect for example)