Using Nagash in 8th

[It's also a hammer]

Hi. Just bought Nagash to go with my Vampire Counts army and was wondering about the best way to use him.
My main opponents are WoC and these are now Legion of the Everchosen so will be facing skaven and Archaon at some point as well as "That" Nurgle Daemon Prince combo that was doing the rounds a while ago.
Cheers

[Sexiest_hero]

If you can Keep Nagash out of range to be blasted by anything you can just wear down the Chaos army. That meanks killing Skaven WM asap.