While playing the latest version of this pack, I would randomly see a fire effect floating around at high speeds, which turned out to be an invisible super fast zombie burning in the sun. It ran right up to me and did massive damage (Well, massive for Bronze armor) killing me in 1-2 hits. I've now seen a few of them, the last straw being one which was wearing a gold helm, meaning I couldn't simply wait for the burn to kill it like I had been doing with the others I had seen. This can't possibly be an intentional thing, they're not killable under normal circumstances as far as I can tell, and make travelling rather difficult. Has anybody else run into these abominations? Are they a bug or intentional?