Yes, I do think his DF can tap into the underworld literally and actually call upon their powers, a sort of "icy Ghost Rider" in a way too.
I am actually 100% certain he's going to contact the souls of his former crew when he reunites with Laboon and reunite them all as ghosts to play one last live conert for Laboon, before they can truly pass on. Laboon might even finally be able to rest once and for all, finding peace and calm finally and joining them in the afterlife. Or at least live the rest of his life happily and looking forward to reuniting with them properly eventually, as well as being overjoyed and glad to see Brook is still "alive" and around.
I am actually 100% certain he's going to contact the souls of his former crew when he reunites with Laboon and reunite them all as ghosts to play one last live conert for Laboon, before they can truly pass on. Laboon might even finally be able to rest once and for all, finding peace and calm finally and joining them in the afterlife. Or at least live the rest of his life happily and looking forward to reuniting with them properly eventually, as well as being overjoyed and glad to see Brook is still "alive" and around.