While this is a funny read of a "post-posthumous" version when you are used to all the other posthumous boss version in Isaac and get a "revenge boss" based on a boss that was seemingly dead to begin with, I'm not quite sure this is right.
Initially I would have looked at it as an alternate skeletal variant of this undead boss, but it does in fact appear to be the posthumous version of The Haunt:
Interestingly enough, despite being a ghost of some sort, The Haunt does reveal a skeleton underneath his "skin" during some of his animations, which is pretty much what we're fighting here. Has anyone ever asked Edmund what kind of creature The Haunt is? It seems like The Haunt isn't the incarnation of someone deceased, but in fact might belong some odd "race" of poltergeist where its "ethereal exterior" is more like a kind of skin with a skeleton underneath similar to (other?) living creatures. What kind of "aliveness" are we talking about here? Did The Haunt even "die" when he came back as The Forsaken? Is The Forsaken the returned form of The Haunt to begin with? <\overthinking> --MudNuts (talk) 11:30, 14 November 2015 (UTC)