Prana is the Sanskrit word that refers to the "Life energy that permeates the Universe on all levels" incliding in animate and in-animate objects. More specifically, it is also considered to be the inhaled breath (air), thus being able to influence all living beings. Suitbale for a spy faction whose modus operandi would be to inflitrate and influence the other factions. Moreover, since this just references 'energy', it aligns with the faction being corporeal/wraiths without a physical body.