Nightmare's whole gig is getting control of the "waking world" any way he can. He has his own "beach head" with the island from the Hulk story "Tempest Fugit." Trauma makes sense for his next Big Plan, as he can literally bring nightmares "to life."
Speaking of "beach heads," Blastaar doesn't have control of Prison 42 anymore? That actually kind of sucks, though I'm hoping the inmates are still part of Blastaar's army.