It's part of the heroes and villians optional plug in for Wars in Skyrim. They are badasses. I saw one lady kill 2 mammoths and 5 imperial soldiers.
Yeah, they're really badass. I disabled that specific feature cause they were just too sick. It's for people who's already beating the game at Master, and my character is way too balanced for that. If I had put every single perk into combat skills, smithing and enchanting I would have had a chance, but not if you aim to play the game balanced.
I enjoy the other aspects of this mod, tho. It's super cool to run around at night and then see the moors outside Whiterun lit up with fireballs and lightning cause there's some epic battle going on. Here's one I came upon last night:
http://i41.tinypic.com/egsldd.jpg
It's kinda hard to see what's going on cause it's dark, but trust me, it was an epic all out battle. I encountered the rockcrab and the spider fighting, and then I was followed by a bandit who joined in, and then came the dragon. The spider killed the bandit, the rockcrab killed the spider, the dragon killed the rockcrab and I killed the dragon. Circle of life b*tches!