I don't think Bua will use black magic because there's not enough episode to make Pra'ek all of sudden becomes stupid. I would be disappointed if they go that route.
I like that Bua isn't all that successful with her plans. Everything she wants seems to be drifting from her. She's such a fool, could have had it all but because of her selfish self she ends up losing the man who would have loved and give her the world had she just stick by him. Oh well, some people will have to learn it the hard way.