On a few occasions I have been attacked by 2 star wolves in the evening while digging pits for silver mining. It helps to be in a mountain biome with Fenring out'n'about. The first one I got was on a mountain biome with no silver, drake or obsidian, but it did have lots of Fenring. After being attacked and killing a 1 star, I dug a taming pit where I was attacked, and the next evening a 2 star showed up. Foolishly I let the 2 stars 2 packmates live as I tried to kite them into the taming pit and was killed. 2 nights later a 2 star showed up, so I killed its 2 companions on my run for the taming pit.