Coprophagus' Tetragon - birth of a daemon army

Here's the concept and the initial 500 point and final 2000 point lists for my Warhammer 40k Chaos Daemon army. I'm a little behind, so I'd better get to more building and painting!

Concept:

There are whispers in the warp of an immensely powerful artifact hidden in the mortal realm– one that could open warp rifts on planets at will, trapping those planets in the rifts and transforming them into new daemon worlds. The four great powers have put aside their conflict for the moment, willing to cooperate as such a device will provide them so much amusement…and also so many new opportunities to tip the balance of power in order to favor one of those Dark Gods. After a trial of combat and cunning lasting centuries, the Great Unclean One Coprophagus was chosen to lead the forces sent to recover the artifact. And to make sure that Nurgle could not abscond with it, Khorne sent its great champion, Skulltaker, to assist…and be ready to add Coprophagus’ rotting skull to his cloak should betrayal rear its head. This unholy tetragon now searches from planet to planet, sacrificing whatever mortals it finds in the hopes of raising the hidden artifact.

Coprophagus' Tetragon

500 point list:

10 Bloodletters - 160

7 Plaguebearers – 105

3 Flamers of Tzeentch – 105

4 Fiends of Slaanesh – (unholy might) – 130

Total – 500 pts

2000 point list:

HQ

Coprophagus, Great Unclean One – (cloud of flies, aura of decay) – 185

Skulltaker – (juggernaut) – 175

Elites

3 Flamers of Tzeentch – 105

5 Bloodcrushers of Khorne – 200

Troops

10 Bloodletters – 160

10 Bloodletters – 160

7 Plaguebearers – 105

7 Plaguebearers – 105

10 Pink Horrors – (changeling) – 175

Fast Attack

10 Seekers of Slaanesh – 170

Heavy Support

Daemon Prince of Nurgle – (Mark of Nurgle, Iron Hide, Cloud of Flies) – 145

Soulgrinder – (Phlegm) – 160

Soulgrinder – (Phlegm) - 160