I think that both practical and CGI effect would be necessary for a Necroscope film. Think of how good the Uruk Hai looked in the LOTR films, or ALL of the Orcs and otherwise tortured things looked. They were terrific! Most up close shots were of actors and actresses in heavy facial prosthetics that looked fantastic! But the wide aerial battlefield shots were CGI. It's a balance between Practical and CGI. It's not necessary to use CGI throughout an entire film. But on the other side of the coin, you would'nt want to use a Practical effect for a Wamphyri close up in a bloodlust rage when it's teeth are shredding through it's bloody gums either.
It's like when Nathan got the killing eye from Eygor Killglance: He had to use it sparingly, else he could potentially screw...things...up!
I think the most diffucult thing about making a Necroscope film would be deciding which novel(s) to include. I've not read through the other threads about the potentiality of the film, but I'd assume the the first novel would be the basis. I just finished Bloodwar, and I must say that after travelling through eight terrific novels, it's gonne be tough! I think the Vampire World trilogy was just utterly amazing!