There are many things out there,
dancing in the wilds,
past the realms of Men,
screaming through the Feywode,
begging, to be, let in.
O, bringer, bringer, bringer beware.
The most (relatively) common creatures from the places outside reality exist in the nearest of the outside realms, the Feywode. Such beings can be thought of as symbols made physically manifest. Angels are virtues and graces. Demons are vices and passions. Fairies are mischief and surprise. Goblins are pettiness and loathing. There are many other such things.
It’s important to remember that these creatures don’t necessarily have these qualities, but instead exist to perpetuate these qualities. This is what makes them all equally dangerous.
The Summon spell simply broadcasts a mystical imperative out into the multiverse at large. It spits out a huge deal psychic energy in all directions with two simple commands attached to it: “Come to Me.” & “Obey Me.” Anything may answer this call.
It’s a wonder this effort ever pays off.
True Name Summoning makes use of much the same energy reserve, but directs all the efforts towards a singular being with the singular command, “Come to me.”
In its simplest form, True Name summoning requires only that the Name of the creature be spoken imperatively thrice. Doing so will always draw the attention of the being and invites it to come into this world. If it decides to show forth, it will be free to do as it will and stay in our world.
A would be summoner can also build certain mental images, exquisitely wrought psychic landscapes and scenes, to help draw in the creature. For instance, a demon of languid pleasure may be drawn to the image of a reclining nude wrapped in red silk and devouring an overripe plum. A goblin of schadenfreude may be called in by the image of man trying to hide his smile in a funeral procession.
Further, one seeking to summon such creatures can increase one's chances by having present symbolic items or states of being associated with the creature’s central concept(s). For example, ripe fruit, fine wines, and being in the afterglow of an orgasm would all work well to attract the pleasure demon. An insincere note of condolence could serve as bait for the goblin mentioned above.
If a summoning circle is drawn, the creature will instead be trapped inside, should the creature answer the summons. (This possibility is why creatures are so reticent to accept invitations from strangers.) There are many designs for such, and most are constructed from chalk, blood, gold, silver, or iron.
The creature will remain trapped within the circle until the circle is broken or the summoner releases him/her/it. It’s common for a summoner to barter with the trapped being for its release. Usually a set term of servitude, a specific task, or a magical boon is requested. The creature will obey only the letter of such agreements, and many will actively attempt to subvert the summoner’s goals.
(This is all written with LotFP in mind.)
Summoning has a basic 1/6 chance in success.
Creating at least one mental landscape per HD of the creature increases the odds by 1/6.
Having at least one piece of symbolic bait per HD of the creature increases the odds by 1/6.
Being a Magic User increases the odds by 1/6.
The odds are also increased or decreased based on the summoner’s Charisma modifier.
Summoning of a specific being can only be attempted once every lunar cycle.
Remember that these beings are for all intents and purposes eternal, waiting around for a few centuries trapped in a circle may not be a big deal to them. Especially if this will mean that they are free to roam the world once the circle is broken. (Killing a creature only sends it back to its own realm. Gotta kill 'em on the other side to be rid of them.)
Trying to summon an actual god this way decreases the base chances and modifiers to 1/100. Summoning a god can only be attempted once. Assume gods have 10 HD for the purposes of mental landscapes and symbolic bait. Gods are NEVER happy that you have dared to try this; welcome to curse city.