From what i know, there are 2 cases of how Dagdala interact with people:
1. People with shadows:
-When the caster draw the magic circle of Dagdala on the enemy's shadow, it force everything with a shadow in a radius to obey the spell specific rules. The rule is that they can only damage each other through the shadow, so they are invulnerable to both the damages and the forces that are done to their body. Damaging the shadow of a body part mean the damage is transfer to that body part, so lets say you damage the shadow of the hand of your opps, only their hand will recieved the damage, same with the torso, the head, ....
-A thing you can also do is to "remove" or "relocate" your shadow so you are completely invulnerable to force and damage because they can only damage you through your shadow, if you do not have a shadow then you can not be damage or push back. This is done by Anos by using Venuzdonoa.