Avatar

An avatar is a physical manifestation of a deity.  The Crystal Kings are each the Avatar of a different god and are unique in that they are not summoned but born from mortals.  When an Avatar is destroyed, the deity channels power through the Great Crystals into the chosen unborn baby, to cause the birth of a new Avatar.  Many avatars are the Kings of the civilized world and each ruling King presides over their own city-state.  All of them are easily on par or beyond the greatest of mortals, even so, an avatar's power pales in comparison to the deity it represents.  The loss of an avatar does no permanent damage to the deities represented by the Kings but is seen as an divine affront and a reason for war.