Bound spirit
From Guild Wars Wiki
Note: The following article use the term "spirit" in the general sense of ghosts, as opposed to the creature type Spirit created by Rituals.
Bound spirits are spirits of departed mortals that have been summoned back to the mortal world and bound in a physical shell to the service of their master.
In Factions, Shiro Tagachi abuses his power as an Envoy (which gives him great powers over the souls of the dead) and binds spirits to his evil bidding. This is done through the use of Spirit binders, constructs devised by Shiro. The spirit binder provides the spirits with a mortal body to fight in while Shiro's power binds them to his service. For this, they are called the Shiro'ken.
The resulting creature, however, does not posses skills and powers depending on the bound spirit itself but the same skills per profession (i.e. the bound spirit of any past Elementalist will have the skill set of a Shiro'ken Elementalist). Except for bosses, all bound spirits have the skill Song of the Mists.

