This article will explain the concepts of ego, tulpa, and archetype as far as they relate to my magick. Here's a diagram. With an example of Sekhmet, there's the abstract concept of Sekhmet(archetype), there's the shared interpretation of Sekhmet(egregore), and there's the individual interpretation of Sekhmet(tulpa). I'll start with the most external and work towards the more internal concepts.
This concept is highly abstract and not required for practical application of magick. The digits of pi are theoretically infinite. This software is a proof of concept that one can scan the digits of pi for any arbitrary pattern. One could theoretically find the entire Shrek movie somewhere in the digits of pi. Those digits existed before the film was created, and will exist long after the movie has been forgotten. In this sense, there exists some reflection of any pattern we can imagine. Anything that can be serialized into binary can be discovered in the digits of pi, and therefor artifacts like bodies of text, movies, sculptures, and images are all reflections of infinity. The simplest way of saying this is "everything that actually exists has always theoretically existed".
Though there might technically be an infinite number of archetypes, there are many that are many that we as humans would group together. For instance, "Sekhmet wearing red shoes" and "Sekhmet wearing blue shoes" are similar enough that we might not consider them two separate archetypes. There are additionally limits to the human imagination. We cannot, for instance, imagine 7-dimensional spaces except in an abstract mathematical sense. This means that out of all of infinity, there's a particular section/partition/area that is accessible to the human brain. Furthermore, we will narrow this human partition of archetypes down into those that can meaningfully relate to the experiences available to a human living on Earth between the beginning of recorded history and today. This narrows the scope of archetypes we can expect to find in artifacts from the past. For instance, base 10 mathematics are easy for creatures with ten fingers, but perhaps a different number of fingers would have influenced our mathematics, and have ripples in our cultural, artistic, and political imagination. This aligns with the notion that geography shapes the cultures of the people that live there. By the accident of circumstance, a culture in a desert region rarely if ever interact with snow, and as a collective may simply not have a word for it. This doesn't mean the people of this culture are incapable of learning what snow is and creating a word for it. Instead, this is to say that the path of least resistance is ignorance of snow. Even when connected to the internet, reports of snow and images of it will not amount to the first-hand experience of snow, and this will have effects on the imaginations of those living their entire lives in said region. So too, humanity lives within a particular set of conditions on Earth, and though it can speak theoretically/abstractly about a much broader range of experience, it can only draw from the experience of its more narrow range of lived experience. The simplest way to express this is "though archetypes are infinite, human imagination is not".
For our intents and purposes here, an archetype is a cluster of different ideas that share similiarity(regardless of what color shoes Sekhmet wears, she is Sekhmet) and exists within the reach of our imagination. This clustering is subjective(one might consider Jesus and Yahweh two separate archetypes, or merely two aspects of the holy trinity), so I won't try to count them. Instead, I'll merely say that there's a finite amount, and we've discovered some of them. See my series on astrology and various energies for clean distinctions. Less can be more. Santa clause, Jesus Christ, and Jupiter might genuinely work interchangeably for the purpose of "old, kind, gift-giving bringer of morality and good news". For that reason, I'd start with some of the existing arrays of archetypes(astrological signs+planets, Sephirot, kemetic pantheon, tarot minor+major arcanas) and expand from it when it makes sense.
A wad of dollar bills is an artifact which physically exists. "50USD" is an idea in our imagination. And yet, it would be innacurate to claim currency has no effect on the physical world. Currency is only one example of an archetype that can reach out from the realm of infinite possibilities, through the finite imagination of humans, and into the physical world like a creeping tentacle. "The United States of America" is an archetype and an abstraction, but it is also alive with a heartbeat. If you threaten the interests of the US government, its white blood cells will come to you in the form of law enforcement, military, or spies. If you exist within the US, it will siphon resources from you. A process may require one hundred steps. If an egregore can compell a hundred people to perform one step each, it succeeds in performing this process. Stochastic terrorism operates by this same dynamic. Merely demonizing someone publicly may lead someone may result in their death by other hands. Said concisely, egregores are archetypes which may act on the world via illocutionary force.
Suppose one learns of some holy figure called "Santa Clause" who delivers presents to good girls and boys each Christmas eve. They studiy the religion of santa clause through artifacts giving Santa's lore. They even participate in rituals such as decorating trees, carolling, or giving presents and claiming they are from Santa Clause himself. Doing all this, one interacts with the archetype of Santa Clause and of its egrgore. However, this is not sufficient for a tulpa of Santa Clause.
To cross that boundary, one might dress up as Santa Clause in the mall, say "Ho, ho, ho!", and improvise responses on the fly while pretending to be Santa Clause. One might also simply ask "Would Santa consider me naughty or nice for this action?" a few times. In either case, you build a thought form. A thought form is an entity which can make decisions on its own in a relatively self-contained way, distinct from your ego. It must draw from your memories, but it will process them in a particular way. One might think "swearing isn't always naughty", but their inner concept of Santa Clause might disagree. It is the ability for a tulpa to view the world distinctly from your ego which grants it utility. For every archetypal energy, there is an archetypal intelligence. You might think "angry me would interrupt that person" but "relaxed me would let them say their piece regardless of how I feel".
A tulpa requires some level of thought to operate. While the related activities may be committed to reflex, at some point they generally begin as conscious thought. "Will Santa bring me presents if I do X?" might lead to an intuitive distillation of Santa's rulings. In the same way, one "reads the room" by checking a potential act against their inner mental versions of the people they are talking to. If you know someone well, the thought form for them will be highly refined and you might effortlessly guess what pleases or displeases the real person by referencing it. The curse of knowledge leads people to forget this time and lead them to assume these internalized processes are innate/"common sense". However, if one tries, they may consciously realize they are already using tulpas in everyday life. Generally, the practice of tulpamancy involves interacting with tulpas in one's mind palace, however. The simplest explanation of the mind palace is that it's the space in your mind where the tomato is created when I say "imagine a tomato rotating a few inches off the ground". Folk with aphantasia may not have a spatial mind palace, and I don't know what it's like to be them in order to circumvent or compensate for this.
Suppose you run D&D games. One of your players always plays an aggressive fire mage. The characters always blast every character they encounter with the fireball spell, no questions asked. They might have played ten of these different characters, but it's very easy to see the common thread of them. They are all the same archetypal fire mage. Each particular character is merely a new incarnation/emanation/costume/avatar for this fire mage. There's high emotional bleed between the character and the player. If a goblin insults this fire mage, it enrages the player, not just the character. All ten of those D&D characters can be distilled down to this "fire mage" archetype, which is itself a more specific version of the player's ego. One might find that the various characters under this "fire mage" archetype have dark, edgy backstories. This tend might be a projection of the player's own subconscious grappling with trauma. The point is not that the player believes they are an archetypal fire mage. It's more that the myth of the fire mage resonates deeply with their own inner psychological world. This player is an extreme example of someone with strong attachments that act to clearly identify where their ego is present. The archetype of "fire mage" is an emanation of their go, a branch of the broader tree of their identity. The ten fire mage characters are in turn branches of the broader "fire mage" branch. A D&D game may take place on a computer screen or on physical 3D terrain, or it may take place completely within the "theater of the mind". Regardless, a D&D game causes the player's imagination to reconstruct what it is experiencing internally via the mind palace.
You may run D&D games. When you do so, the world, the weather, and the goblins are thought forms and at best tulpas. A player might kill a hundred goblins and you might cheer them on without flinching, yet you might still be able to come up with dialogue and decisions for the goblins on the fly. These are clearly tulpas. If you create a recurring character and find yourself feeling hurt when the adventuers kill it above and beyond the loss of time and energy invested in the entity, that would be a good indication said character was a reflection of your ego. Some part of that character was "you", and "you" were invested in that character. In a way, killing that character was killing a part of you. This is a common phenomenon in modern D&D culture in which player characters are used as canvases for players to paint on and player character death can feel like having a part of the player has just died.
The simplest rule of thumb for picking between an ego and a tulpa is "am I directly experiencing what this entity is?" If the answer is no, it's a tulpa. If the answer is yes, it's some incarnation/emanation/costume/avatar/aspect of your ego. The unexamined mind is assumed to have one ego. While this may be true, I find in myself that I've got four distinct egos. By creating many avatars of your ego(D&D character, story character), you might be able to tease out common threads to distill down one archetype, or might find multiple. In either case, you can use your ego in your mind palace to interact with tulpas to regulate emotions, analyze via dialectics, and expand the range of archetypes your imagination can access. Through creating art artifacts and otherwise interacting with other people, you may create or alter egregores. Future articles may address these concepts in-depth.