This well of light shining from heaven was Grace's level 99 skill, the Divine Penance. It was an AOE offensive skill that dealt light and soul element damage. The best thing about this skill was it only affected the enemies. So, even though Jack and Grace were also bathed by the light, they were unharmed.
When the well of light fell on the demons, they found their bodies becoming extremely heavy. They had difficulty moving. As they struggled to move, the shooting stars came to them. When those shooting stars arrived, they discovered they were not shooting stars. These shooting stars were hungry spirits composed of light. Their faces expressed extreme hunger. Their mouths opened wide as they attempted to devour the souls of those trapped by this light.
Damage number over damage number kept popping up on these demons as the spirits crashed into them.