Evocation is the act of calling upon or summoning a spirit, demon, deity or other supernatural agents, in the Western mystery tradition.
Comparable practices exist in many religions and magical traditions and may employ the use of mind-altering substances with and without uttered word formulas. The user can summon spirits from beyond the grave in order to commune or serve the user.
Triggering The Power
The user can transport person, creature, or object of choice by means of Teleportation, Dimensional Travel, Portal Creation, or some other way. This may also result from a previous summoning contract, which creates a connection between the summon and summoner.
High-level users may not be bound by restrictions such as a contract and can summon anything they want, including powerful beings or "familiar spirits" and often require strong mystic connections to where these entities reside. Users can call upon fairies, angels, demons, or animal spirits, just to name a few.
The summoning can backfire, however, leading to any number of misfortunes, such as the summoned person, creature, or item causing harm to the summoner.
Klaus is also able to conjure spirits and manifest them into the real world. In his first attempt, when trying to summon Sir Reginald at the funeral, Klaus states he couldn't do it because he was high. Also because Reginald was too stubborn to get a hold of. With his newfound attempts to remain sober, Klaus was able to physically interact with Ben's spirit for the first time. This later further evolved where he was able to manifest Ben's spirit into the real world, though temporarily. In an alternate 1963, he was able to conjure deceased American soldiers into fighting Soviet soldiers. After he was blasted back by Lila's energy wave, Klaus was also able to conjure two ghosts into catching him in their arms just before he hit the ground.