Bushido;
Dark Void: - Going to need a second opinion on this, as it looks like it is essentially an unavoidable attack that places someone in an illusion for x amount of time. Mind control, for example, is usually not allowed in these kind of things, and this illusion at the very least, takes a step into the same realm of attack. It's perfectly fine to create illusions (as in, constructs that aren't really there), but Dark void seems more like an hypnosis, and that's a no no.
Power of decay: Destroying metal is cool and all, but add the following; "This only works on tiers lower than himself, unless he preps it." - As to avoid other fighters who don't run around with holy weapons (few do) having their superpowered magic weapons destroyed easily.
Black plague: - Be more specific. How fast does it kill someone? Use Alex as an example; how fast would it take him down? If you're using it as an actual black plague, keep in mind that it took quite a while before people fell over dead by it. Do people need to inhale the black plague he spews forth for it to affect them? How fast, and long, does it travel?
Regeneration of the damned: No head regeneration. If you get beheaded, you die.
Metamorphous; Need a second opinion. What was Skallagrim's stance on transformations? This seems like a super sayan progression to me, which I'm pretty sure is a no go. I might be wrong on this.
Final form: If he dies, he dies. Death is the state of which we measure a defeat, so if he comes back every time he dies, more powerful than ever, then the fighter who killed him (who at that point is, without doubt, pretty fucking worn out), is almost guaranteed to perish. I'm going to deny this ability, unless any of the other character reviewers have any objections.
Pure dark: The ability to not be fooled by any illusion is not the same as seeing every illusion for an illusion. An illusion is a construct that isn't really there, a false image, a projection. To varying degrees. Does he automatically go "Aha, I am not fooled by this!", or does he actually see through them? If the latter, change your wording, and be aware that even if he can see through them, they're still there, unless stated otherwise in the illusionist's CS. As far as I can tell, we don't have any of those, so this shouldn't be an issue. I'm just making sure we're on the same page now, in case one of those pops in later.
Power from the sinners: No. Doubling in power when he meets an evil presence of sufficient power? That's every evil character in this place. Your character is good aligned, so that's most of the dudes he'll be fighting. Outright denying this ability. It's a permanent doubling of his powers nine times out of ten.
Scythe; Summoning the Cerberus requires preps. The amount of such will be decided when you've written down a separate sheet for Cerberus in your CS. As a summon, it needs to be more specific.
Monster strength: Specify. We don't know how fast you think demons run, or how strong Hercules is, or how durable he is. Give us some numbers.
That's all, for now.