Regarding Mizora, I think she made more sense in Wyll's old story from EA. He had a darker side to him, and was driven not only by wanting to protect people, but also by revenge. Had Wyll continued on that path, he'd likely become corrupted by her eventually, and turned evil.
In this new story Mizora doesn't make sense anymore; she doesn't get anything out of Wyll using her power for "heroing", so why would she even make a deal with him? The entire 'corruption' angle is reduced to killing Karlach, and the set up is too obvious for someone who is supposed to be part of Zariel's court. She is very easy to outsmart for someone who has centuries of experience trapping people in deals.
