The glottkin (consult the book for points)

Herald of Nurgle (205 points)
+ Fecundity
+ Battle Standard bearer with Razor Standard

35x Plaguebearers in horde formation (500 points)
+ Plagueridden
+ Musician
+ Standard bearer with Standard of Discipline

So the optional I have left and I want to spend the rest of my points on special and at least 1 rare.

(Special)
Nurglings
Beast of Nurgle
Chosen
Chaos Knights
Putrid Blightkings
-Please feel free add more because I am daemons player I do not possess the warrior of chaos book or beastmen as of yet and I am basing the choice of the warhammer webpage based on pictures of what can be represented as nurgle but not to the point as a count as-

(Rare)
Soulgrinder
Hellcannon (easy to make into nurgle and make a plague cannon)
Plague Drones

Please note I will only ever add models to the army not for wining but to make the army awesome in a nurgles mindset