
The protagonist prefers five-pointed stars, but states that he's used to amateurs using triangles because they're easier to draw.The Dresden Files uses circles a lot, occasionally with other figures (like the Seal of Solomon, a pentagram, or a triangle) in it.
Any of them could open a gate to Leviathan (hell) or summon, banish and control cenobites (demons) by finding the correct geometric state in the puzzle.
THE MAGIC CIRCLE TROPES SERIES
The Lament Configuration of Clive Barker's Hellraiser series and adaptations had variations in puzzle boxes and even whole buildings. Ghostbusters even has a reference to this Dana's apartment building was designed by a group of cultists in the 1930s with the specific purpose of serving as a "spiritual array" for the summoning of Gozer. Mahoujin Guru Guru: Kukuri's Guru Guru magic requires her to trace magic circles along the ground around her to cast spells and summon. Generally the more complex and powerful the spell, the more complex the circle required to activate it. Other spells also require circles to be drawn (or created out of Instant Runes), but as a mage grows more experienced with that spell, they lose the need to draw the circle. The pactio spell in Negima requires a magic circle to operate properly. There are at least 4 known variations, 2 of them corresponding to major schools of magic and one to magical specialisation. Related: The Instant Runes in Magical Girl Lyrical Nanoha adopt different geometric shapes dependent on the class of magic the caster is using. Then, in the opening chapters of Tsubasa Reservoir Chronicle, we see several different forms of magic perform the same function - sending a person or persons to the Witch of Dimensions - each with their own special magical designs.
CLAMP's Cardcaptor Sakura 's title character formed a circle with astrological signs in it when she performed magic with the Clow cards and wand, (and later a different circle when she formed the Sakura cards). In the manga this is why the Big Bad has to spend generations having a country-sized Philosopher's Stone array dug around the country in order to execute his plan. Consider it a perk of being crippled from attempting human transmutation. You need immense knowledge of alchemy to pull this off this is why the only people who can do it are ones who have opened the Gate. The rest of the details of the array are held in the alchemist's mind. Ed, Izumi, and Al don't have to draw the circle, but the series explains that they are still forming an array: their clapped hands form a circle out of the body/arms with a simple triangle on one end. that's why people using (or "being") a philosopher's stone can transmute without a circle. Averted with philosopher's stones, which as a secondary feature allow the user to transmute things without circles. However these things are all drawn ridiculously fast, with the most Egregious example being drawing half of one on two tables, and shoving them together, each taking about half a second. They're called "Arrays" and most Alchemists have to prepare them beforehand on items they possess or their bodies e.g. Some of the symbols are actual alchemical symbols used way back when people were experimenting with various metals, chemicals, etc, and used the symbols to keep track of what they were doing).
The relationship between the various transmutation circles is never explained, though it's implied that more complicated designs are required for more complicated alchemy (a very basic transmutation circle consists of nothing more than a square inside a circle. Fullmetal Alchemist: Alchemy requires "transmutation circles" that are essentially Geometric Magic.Examples of Geometric Magic include: Anime and Manga