Because of the loyalty, a lot of monster groups were more menacing and dangerous when there was a mother monster there.
After all, the children of the mother monster would become the greatest army for the mother monster.
Everyone could not see how the hallucination fog worked for the snowball monster, but Delph, as the one creating the fog, could feel the state that the monster was in.
The monster was indeed easily fooled by the hallucination because the hallucination not only blocked the visual, sense of hearing but also the sense of smell.
Taking advantage when the monster was confused by the fog, Delph used his second ability and magnified the monster's feeling of absolute obedience toward its mother.
Even if there were more than one mother, the monster, who didn't have a high intelligence, just believed the hallucination and the amplified feelings foolishly.