Recently I was at a pretty cool lecture and the presenter made the comment that perhaps it's time to toss out the idea of evocation to physical appearance because it just isn't real. He suggested it was an example of something in magic where people are either lying or fooling themselves. The thing is, with the exception of Crowley, and Joseph Lisiewski, there aren't many magicians who I've gotten the impression meant to suggest that they conjure spirits to physically manifest as material creatures. Most magicians don't talk about visible appearance often or physical manifestations, but when it comes up and people are open about their experiences it's usually pretty clear that we're talking about sensory experiences and physical occurrences that are signs of the presence of the spirit rather than creatures building bodies out of nothing.
As far as conjuring spirits goes the important part has never been whether or not you conjure to physical appearance but whether or not you get results from your spirit work. If anything that is what I would stress. Visible appearance is so not an issue that when we look at historical magical works we don't see this concept clearly presented as a criteria for judging success, in fact we see crystallomancy frequently presented as a means of interacting with spirits. So yeah, results, not spontaneous generation of physical bodies.
That said, some pretty cool, pretty clear things happen sometimes which indicate the presence of spirits or the reality of their work. I was talking with a friend the other day and he asked about physical stuff with spirits. It seemed useful to him to hear some stories, and I figured talking about stuff that happens and what physical manifestations are might help newer conjurors who are worried about whether or not they're missing out by not having partial legs materialize in their triangles.
So let's tackle evocation to visible appearance first. Spirits making bodies out of incense. This is kind of true, but not in the sense of turning smoke into flesh. Since Poke Runyon a lot of people have interpreted the incense, and the mirrors, and the crystals as a way of tricking the mind and allowing for a psychological projection that we can interpret as a spirit. But, spirits aren't just psychological projections, and the results of real conjure work are more impressive than squinty distorted misapprehensions.
Incense is traditionally burned as an aromatic offering for spirits. There is a traditional view that prayers were carried upward on incense, but intermediary spirits were also once thought to be the means by which this is done. So incense has a traditional connection to the working of spirits. Traveling through the air also being a traditional association of spirits incense connects back to this nature giving substance to the otherwise insubstantial air. It connects to three of the four abodes of spirits, aerial in the smoke released, terrestrial in the material burned, and infernal in the fires which stir the smoke from the body of the incense. As an offering, with its intermediary spiritual nature, incense becomes a material focal point for the spirit which is gifted to the spirit and therefore feeds the spirit adding a material component to the force of its manifest interaction with the physical world. So no, the incense doesn't give a materium from which the spirit can build a physical body, it provides a physical substance the spirit is able to draw on in strengthening its anchor to act in the world. Crystals and mirrors likewise have physical and esoteric properties that allow them to serve as links between the spirit world and the physical world making them, like incense, useful tools in interacting with spirits. But not tools for transubstantiation ala Weird Science.
So what things happen when a spirit shows up? Sometimes the temperature changes. I've been in rituals where it's gotten dramatically warmer typically, but a few where it's gotten cold. Sometimes the incense will shift and start to form a more consistent cloud in one area rather than become diffuse through the room. Sometimes there is a shift in the air, almost like when you see rippling from heat off a black top. I was leading a conjuration once where afterwards I spoke with several people who attended and they noticed the same thing I noticed, a particular part of the room where the spirit showed up during a particular part of the ritual (not near the designated area or when he was called directly) and initially he seemed to give off a sense of criticizing the method we were using until we got to the God names, at which point he moved to the appropriate spot and seemed more attentive. About 5 people all had this same response and discussed it independently, but nothing visible or physical happened on this particular conjuration. I've had stuff turn off or on, fall over, candles produce concerning amounts of fire, things like that. But usually it's mostly just a “Hey, I'm here, what's up...oh, ok finish conjuring me and then we can talk” kind of impression that cues me in to the presence of a spirit rather than the cool physical signs.
Much cooler than those kinds of physical signs are ones that occur as a sign that stuff is going on rather than announcing the presence of the spirit.
A really neat one I had several months back actually had to do with the spirit leaving. We had finished the interaction, there was fire burning as a place for the spirit to be present. When we were wrapping up the interaction I wondered about if it was appropriate to just put out the fire or let it burn out. When the spirit left, the fire immediately went from a decent size fire to sputtering and going out.
A couple months back I was about to get cozy with someone on my couch, reached in my pocket to grab the Venus talisman I carry, and at the time I had just recently done work with Hagith, the Olympic spirit of Venus, and Hagith's seal was still on my altar, with my crystal sphere sitting on it. The sphere sits there every day undisturbed, the planetary disk on which it sits has a ridge to hold it in place. With nothing disturbing the altar when I reached to grab the talisman in my pocket the sphere rolled off the disk, off the altar, and across the floor to the coffee table in front of us.
Years ago, and this one is one of my favorites, I was leading a conjuration of Raphael in his office of Archangel of the Sun, for my local OTO lodge. We were focusing on healing in the community. The ritual left me pretty drained, it was one of my first few Solomonic conjurations and the first one of an archangel. I believe it was my first public one as well. We went to a Pagan coffee house event afterwards. On my way home, in the three miles or so between getting off the highway and driving across town to my house I passed six ambulances. Not only were there six, the number of the sphere of Tifaret, but all six were at homes actively helping people. Usually when I see ambulances while driving they are driving around, but in this case all six were stopped at homes with medical personal deployed into these homes. Clearly not a sign of “physical manifestation” of the spirit during the conjuration, but a neat manifestation of that force within the community surrounding the place where we did the invocation. Also, several people reported their healing intentions having worked out...but, numerologically significant ambulances are WAY cooler.
Last fall I was building an altar for a spirit I was working with who resides in some liminal places. I had gotten most of what I needed but he wanted a walking stick. I couldn't find a good one in the places I went and so I resolved to get it within the next few days. The next morning I was heading to work, got to the end or my street and in the middle of the cross roads was an old black wooden cane which was exactly what I needed.
Sometimes it's pretty physical signs that work is being done to fulfill what you asked for. Another recent incident involved asking the gnomes for money for some stuff and the next morning getting in my car to go to work and finding a $50 bill in the door. Sometimes you do work with a spirit and then find something which is a traditional emblem or offering for them. Sometimes they teach you stuff and then books turn up, or you find stuff you weren't looking for in books you happen to be reading that confirms or further explains what they were showing you.
I'm not someone who goes on a lot about synchronicity. I think if you lead a magical life in the sense of developing yourself and your world to be harmonious and in synch yeah you'll start having a lot of synchronicity because the work you're doing will be harmonious with how your world is moving.
Work with spirits is different.
You'll have stuff happen that is a byproduct of the spiritual presence (like the ambulances), but you'll also have stuff happen that is the direct hand of the spirits showing you they're doing the work you asked for even if it isn't immediately done yet (like with the gnomes).
Personally I think having invisible friends who can make cash appear in my car and throw rocks across a room to high five my efforts to get it on is way cooler than having an Owl wearing a crown of diadems astride a crocodile with ape fur manifest in a ball of smoke.