He uses it to do a superhero landing after he gets blasted out the window. You also see it around the green energy blast he fires at Thor. Is it Similar to what Dr. Strange was using with the souls when he was fighting Wanda in MOM and Doom just has better control of it?
Yes Kang was the initial plan. And then they pivoted to Doomsday getting rid of Kang Dynasty. But was Doom always the plan even with Kang. Because after Kang Dynasty they still were doing Secret Wars. With Battleworld, etc… So Kang would rule Battleworld? That part doesn’t make sense. You give one of Doom’s most iconic arcs to Kang the Conquerer? Was there a possibility that in Kang Dynasty that Kang was the big bad and Doom like he seems to be in Doomsday is with our heroes. Seeming like an ally. He helps them defeat Kang, but in the end reveals himself to be the real villain of the movie who has been behind the incursions all along and he then creates Battleworld.
Also Michael Waldron who was writing Kang Dynasty looks like he is going to be credited as a co writer on Doomsday. So they must have retained a good portion of his original script.