So anyone who can borrow the ultimate ability has to give up their freedom and independence. In this lady's case, she has given up everything to be able to display this power.
The power she displayed was the Dream Domain. It was the ultimate ability of the pathway of dreams.
The effect of this ultimate ability is to allow part of the dream realm to descend to the physical world and take control of that part of the physical world to form a boundary where other divine abilities that aren't mental in nature will be suppressed.
The god of dreams had chosen to use this ability because it had a wide range of effects. Since he couldn't see Legion, it was best to use something that acts like a net and can capture Legion in a wide area.
His decision turned out to be correct. Once the ultimate ability was used, the dream realm descended, and the entire area turned a misty white.
