Summoning

Summoning is ritual magic that calls upon another being and allows for it or its power to come to one's aid. Those who apply magic in this way and are the recipients of a summon's abilities are known as Summoners.

Types of Summons

Evocation is when a summoner uses mana  to summon or provide a portal for another entity to appear before them. Evoking is usually performed through warding circles or mandalas, incantations, lyrics, components or through a focus.
Invocation is when a summoner uses their own magic power  to become a conduit for a spiritual entity who can act through the summoner or provide their power to them. Due to its nature, invocation only works on beings with a corporeal body and only with spirits.
Exorcism is essentially the opposite of invocation and forces a spirit to leave a body or object it is possessing or residing in. Generally, this requires a summoner with power currently exceeding the entity it is performing the ritual on.

Pacts

To strengthen the bonds a summoner has with the spirit(s) they invoke, he/she should consider making an official agreement known as a pact. Pacts involve a mage linking their internal magic power with a spirit which allows them to use a spirit's sorcery when invoking them. Conversely it also allows the spirit to use the sorcery of the summoner's race or inhabiting and acting through their body during the invocation. Another benefit of a pact is the creation of a mental link that lets one know when the other is in mortal danger, regardless of distance. Also, if a spirit takes control of a summoner during an invocation, the link of a pact allows the summoner to remain fully aware.
Invocations without an official pact, merely has the spirit possess the summoner until the mage's magic power is depleted and doesn't remember anything during the ordeal.
In order to access each other's power, both parties have to offer a price in exchange. A spirit's price is usually just being on call and granting their power while the summoner's price can range the mage providing the summoned with food, getting them a certain object, being temporarily possessed by the being whenever it wills it, to becoming a servant or lover of the summoned being.

Type

Metaphysical, Supernatural