Shikigami are a form of weapon utilized by spiritualists and Onmyoji. The basic concept behind Shikigami is summoning a spirit into a vessel, and it is common for one to use paper dolls. It is also possible for one to summon them into the body of a person or animal, though this is risky as this gives the Shikigami greater power, and with power the risk of rebellion.
They have a variety of uses, and can also be treated as soldiers or minions instead of weapons. Most of the time, Shikigami are invisible to the eye, so they can be used for spying or assassination. Those who wield Shikigami are considered supporters, as the wielders themselves typically don't do much fighting, with the exception being Onmyoji. Keeping Shikigami wielders in the back will be quite helpful, as the summoned Shikigami can assume more humanoid forms and fight alongside the main combatants. This also means that a wielder can do just fine on their own, assuming that they have Shikigami fighting for them.