That was also Gruenwald. He liked what Stern had done with the character earlier (Incredible Hulk, I think, where Dr Droom first appeared in standard Marvel continuity renamed Dr Druid) and thought he would make a good addition to the team. He was left over for Walt to deal with. Simonson had a much larger story involving the Time Bubble, but he kept getting undercut by editorial interference, which is why he left the book. Eventually he'd finish it in Fantastic Four in a massive cosmic storyline.