so iv been looking at nurgle units for my deamons their are loads of gd choices firstly
nurgle comes with shrouded as standard and defensive grenades which makes them great for digging in.
nurgle powers are also really gd on deamon princes ap2/3 and poison is good for killing high toughness creatures OR biomancy to make them more durable and tank busters
an alternate deathstar is plague drones with full command and plague banner 2+ poison for 1 round. supported by the grimoire and a pair of biomancy princes power number 5 makes them eternal warriors and FNP4+ which makes them 3++ FNP4+ and with T5 and 3 wounds each they'll be very hard 2 shift ws3 and 3 attacks makes them great choices
another great support unit for troops are beasts of nurgle and now that u can summon them as part of malefic powers. what makes these great is they have all the nurgle powers AND if u charge them it becomes a disordered charge AND if another unit charges a freindly unit within 12" of them they MUST charge that unit and these are T5 W4 Ad6+1 so on the charge 3 can have min 9-24 attacks and at 52pts a model with a max unit of 9 they is some deffinate worth to having a proper unit and summoning them
I will also be using standard plague bearers and heralds summoned as a buffer for my precious tzeentch units