he's bleeding black mist...what is the reasoning behind this...even a tiny bit of information would be nice, since i know you can't just give EVERYTHING away just like that.....
my thoughts: unlike other blackmist beings perhaps when nebula is cut he retains his blackmist making it near impossible to kill him??? that can also be how he absorbs the blackmist of minor foes he's destroyed over time....making him more powerful, but since he has soo much black mist energy why does his appearance remain withered... perhaps you can draw a imaginary concept art based off my thoughts making him 'plump and full of life' if you know what i mean... basically the opposite of his look now...
This is NOT any facts, this is just how I a BIG fan of the Contrast/AWW universe see it:
I always imagines nebula as the origin of blackmist, the being who first corrupted the "white-mist" or just "mist" in the world. Dan has described nebula as "coming to this world" seen when he was working on his contrast during his live streams. Meaning that Nebula comes from a different world, now composing of "white-mist", but instead "blackmist".
Because of that he doesn't belong in this world, his essence (the blackmist) constantly leaks out of him, making him weaker and weaker over time.
However, because of that he leaks blackmist, it comes in contact with this "white-mist composed world" and slowly starts to corrupt it, because blackmist is violent in nature, thus transforming Whitemist into Blackmist.
But as because nebula slowly "bleeds" his dark essence, the only way for him to survive is to absorb other blackmist creatures. (kinda like how Network retained his power in Aww3)
I also imagine nebula to have a great control over blackmist and can manipulate it at will, being a "spell-caster" of near divine strength, however every time, and the more he uses his powers, will he leak black-mist essence even more, so Nebula don't wan't to use his near divine powers, because it has a risk of killing him in the process, that's why nebula prefers a more of a background role, instead of directly acting out his wishes, he manipulates other characters to indirectly do his wishes.
That's the way I imagine Nebula, and why he "bleeds" blackmist, and why someone so powerful as him hasn't entered the AWW universe yet, he is there, just indirectly, in the background, letting everyone else to his wishes instead of directly whooping everyones ass.
But as i just, this is just fandom work, nothing here is really confirmed by Dan, and I can only hope to get the full story of how everything is in the end.
*edit* BTW the Nebula picture is AWESOME BEOND AWESOMENESS! *edit*