The formation where Adrian is at the center is specifically created by the four of them. It was based on a special magic circle called the Star of Four. It is a three-pointed magic circle where the middle being is the one that controls the power.
One would think that Adrian will not be the center of this formation because he is the youngest one of them but that is not the basis. The basis for this formation is now flexible the energy of the one in the center is. Out of all of the four of them, Adrian has the balanced qualities for all sub elements of Origin Magic.
Adrian's mastery over time, space, and force has made him able to safely be the driver for the spell formation. This meant that he gives his mastery to the other elders which in turn increases their mastery even more. In exchange, he could tap into the energy reserves of all the other elders which means he can now cast spells that he cannot before.
