I think the asian chick is Aslaugs spy, or atleast she is getting him high to weaken him so Aslaug can gain power. Seems to me Ragnar and his wife pretty much despise each other now!
If they follow real history, or the one or two scenarios about the death of Ragnar, it's the snake pit, or dysentary. I can't imagine Aslaug will have anything to do with it, but it does seem to me that the she sent Ragnar to the Asian chick. She told him to "spend time with her" that she wouldn't be jealous. Those drugs she is giving Ragnar are driving him mad. Lets hope he is still our Ragnar and that he has something up his sleeve. We've been fooled before thinking he had lost the upper hand, and in the end we get a surprise.
What was that vision/scene with Floki and Aslaug and Habard? Floki some how psychically felt her as she was with Habard. They've never been particularly connected.