Having no other choice, the Ice and Snow Princess came to help in this detrimental battle.
She could easily shatter the walls of chaos monsters with her icy powers, freezing the crowd of monsters and preventing them from reinforcing the shattered walls. It allowed some of the Demons who quickly reacted to get inside and ran amok.
Despite being unable to kill the Human Army, they could at least stop their advancement.
It would be extremely hard to isolate some and hostage them so that they couldn't return to the Human Army—with the walls of chaos monsters on either side, but the Demons who got inside were still able to slow them down immensely.
At the very least, the Executor would not have his way easily.
No matter what he needed the Human Army from, they would make sure he couldn't.