What are faez crystals?

The discovery of faez crystals—which are condensed forms of faez, the raw stuff of magic—during the events of the Order of Merlin trilogy upended the balance of power in the Undercity.  The clans that ruled the shadows were the first to use them.  The faez crystals, commonly called "stones", turned clan warriors into demi-gods of physical abilities.  Using a stone requires attunement, which does not always occur under the best of circumstances.  The warriors that do attune to at least one faez crystal are called waku, rather than the normal soldado. 

 Here are some of the known faez crystals and their effects:

 Amber – This stone gives the user enhanced senses which is particularly useful in the shadows of the Undercity.

 Topaz – This stone provides strength and speed.

 Opal – The opal gives the user the ability to heal others and themselves.

 Emerald – An emerald lets the user make their body either really light or really heavy.  But they can only do these for a short time and must balance their bodies with the opposite.

 Sapphire -  The sapphire allows user to push or pull anything imbued with faez (of which the Undercity is rich in); this allows them to knock opponents over with a flick of the wrist, or throw themselves high in the air.

 Black Diamond - The black diamond, the rarest stone of all, provides steelskin which is impervious to nearly any knife or bullet making them theoretically invulnerable.