There were two types of formation.
Ones that used runes and the other one only used the position. To be honest, the one that used position was simpler, but the effect was generally weaker because they couldn't control the mana so accurately. They were also usually used in wider place and could be used to cover a large area.
Many people used positional formation because it was easier to learn. But at the same time, they would need magic tools to form this formation effectively otherwise it would be hard to make a formation in this world with thin mana.
The other formation that used runes were more complicated because they had to recognize the runes and also made sure it was stacked well. There were thousands types of runes and memorizing each and every single one of them was more than enough to make many people crazy. Because even the slightest bit of difference in the rune shape could change the rune's meaning.
