Direwolves will go for you, also I think the Vyre ones do at night. The NPCs that get a little more effective near the Ruins. I think the boss fights are scaled in terms of difficulties.
I think you need to do the bosses in dungeons to get the Ancient fragment type thing which is needed for certain things like egg incubators etc. The boss in the tower was a little challenging for me before I levelled up first.