“ In a deeply unsettled world, much of it anarchistic or ruled by murderous gangs, a group have adopted the armour, weapons and discipline of an army of the distant past.”
“ A ruby of immense size, this stone was once the eye of a deity of war. When properly commanded by long lost rituals, the huge gem will rise into the sky, glowing brightly. Visible for miles, all who look upon it in its full radiance will be filled with intense homicidal rage.”
“ When you sleep, your soul briefly returns to the place where it was created/goes to when it dies, and seeks nourishment. Everybody's soul is created with a little link (or you could say a greater entity calls it back) to that place so that it can return easily, but upon death, the soul returns via that and annihilates the link as if returns.
Also, as an added thingy, you could say the entity supplying the link, or residue of the links themselves, (whichever) is the source of all arcane power.”