I enjoy this show, it's much better than the movie, but finding it disturbing the casual references to demon summoning and things like tannis root. I know tannis root isn't real, a fictional plant/fungus/herb used as a plot device in the novel and movie Rosemary's Baby, a reference that most kids now and a decade ago wouldn't get, but not crazy about the desensitizing taking place in society against violence, the occult and demon (aka old gods) worship. A kid doing an Internet search, even just out of curiosity, on things they hear, like tannis root, can easily be led to some dark places (ex. on first page of search results: Tannis Root The Infernal Sea, released 01 May 2014 Tannis Root - Lyrics. Give to us a child, One that bears your mark, And lead us into the dark days) if parents aren't paying attention & attending to their children's mental and spiritual welfare.
If your kids are watching it, you should be too, and telling them the things that are wrong and why, and how to protect themselves against otherwise enjoyable distractions.