I'm pretty sure, the Dark Sea, and magic pollution is because of Durza freaking out when Theos destroyed his leg, and nuking the planet. A lot of bad stuff can be traced back to and blamed on either Durza, Prometheus, or Cursebeard.
I think Chaos is also a prominent reason as to why the Dark Sea exists since Chaos supposedly wiped out the Old Sea turning it "Dark" Either that Or its that jackass "Edgelord nobody knows that nuked the Old Sea to hell and back" as per Blaze's own words.
I'm the biggest Arcane Adventures/Odyssey lore fanatic I know, and I think this is the first AO video on RU-vid I've watched that didn't get anything wrong and pass it off as fact. Massive props to you for doing your research! I think the line about the magic pollution clearing after 500 years is supposed to mean it clears in the year 2000, despite the line being listed under 1500. So it's just an unclear or poorly-written part of the doc. Magic pollution is still clearly a major thing that hasn't cleared at all during the time Arcane Odyssey takes place, so it wouldn't make sense for the pollution to have cleared already.
a little idea i had for vitality is the idea for vitality variations of magic as we all know magic used to come from the soul and well vitality is related to that so why not add the possibility to stumble uppon islands from that era that still used soul magic and the chance to find scrolls written by the monk(prometheus) who showed this way to do this kind of magic and wen used it gives you the ability to choose what sould variation of magic you would like to use
A fight between smol wizord, prometheus, durza and theos create explosion Pow Now theres dark sea everywhere Edit: ok everyone sure readed my comments and rely on it :( Dark sea basically created by many magic into one then become unstable Just like durza he fused too much magic into him and become purple
Though something weird is that you cant find the dark seas in arcane advenuture/ arcane reborn (or in the seven seas) is this intentional or did vetex just use the dark sea idea in arcane odyssey?
there probably is now, the dark sea is likely only a concept thought of when vetex started thinking of AO. either that or he just didnt add it into AA or OF.
Then again, theos and Warren are old as crap without any curses, maybe Warren but no info there other than tech adding his character in, Could be so and the dark sea pollution did some revival magic stuff or sorts