It’s sort of matters, casting a circle in the shape of a circle will provides certain benefits that you may not get with other shapes, though you are able to cast different shapes such as a square, or triangle.
- Circles provide even protection around a specific point.
- Circles are one of the strongest shapes.
- Circles provide energy to flow in a circular cycle which allows the energy not to get stuck in any corners, and to flow evenly.
- Circles also allow the cone of power to build up through the amount of energy that moves in the circular pattern.
Where the other shapes do also have their own benefits the circle is pretty good in the sense of protection, and power raising, which seems to be why it is use the most.