Legacies Season One Minor Characters

Shouldn't the witch who created Malivore be more powerful than she was shown to be?

She literally created a living, almost immortal dimension. Other witches channeled the full moon, the sun, and even a different celestial event to create dimensions or immortality, but the witch just gathered the blood of a vampire, werewolf and hers to create that creature. She basically used her natural power, just used black magic.

How come in legacies when Hope, Lizzie, and Josie were fighting the mummy, Josie had fire powers without siphoning from anything ?

In legacies there was a dream monster and it could do stuff to people in the dreams and they would feel it when they are awake too. What if the white oak stake was in the dream could it kill them if it stabbed them?