I dont know how much I agree with that mr Karandras.
they are just as likely goign to try hitting the Deamon Prince or Bloodthirster and would take less time to kill than Nurgle Spawns.
Spawns have 6 of toughness and 3 wounds each, they have a 1/3 chance of having a 4+ArSv and pretty easily a 5+/4+ cover save.
5 Nurgle spawns can take an insane amount of bolter fire.
Quick math would say that 1 spawn can take 40 space marine bolter shot if he has a 5+ cover save, that means a team 5 can take about 200 bolter shots before going down this number goes up to 270 bolter shots if they have a 4+ ArSv/CovSav, if he wants them down so bad then he can have them but if he has that kind of anti infantry firepower then he has no chance against this list.
Terminators would not be a bad idea in this list but they dont have the same crowd control power that the spawns have, spawns would be one of the few things i have in my list that will be good against a swarm army and termies wouldnt do too well against this.
also I think the juggernaughts would look better in this list