It's Joe Madureira's work.
He also was one of the main art designers behind the Darksiders series(which people also compared to WoW in art style) and his studio Airship Syndicate, who also made this game, is behind Battle Chasers and Ruined King. You might also recognize his art from his 90s works, Udon collaborations, and Playstation Magazine. I know it's colorful(and that makes people instantly think of Fortnite on this forum for some reason) but once you play the game or look at more footage of it, you'll start to notice the differences in art style and his usage of sharp, sometimes rigid lines over curves.