A Spawnstar Might Work

Nurgle Spawn are nasty pieces of work. They're speedy, tough to kill and decent in combat. About the only thing that can wipe them out quickly is Dark Eldar, Farsight bomb or a Seer Council. We can take measures against such things.

To maximize the effectiveness of T6 models with 3 wounds, you'd like to give them a save. So you run them with psykers on bikes and roll Biomancy to try to get endurance. Against Dark Eldar and Eldar, you would roll Telepathy for invisibility. If you get the right power early in your psychic rolls, you could try for both.

If we are using psykers to maximize the usefulness of the Spawn, we should use the Spawn as an escort for some very strong psykers. With Black Legion, we can get three Sorcerers into the unit without going double-force org, as that is still frowned upon. Black Legion is good because we can sport the Last Memory of Uranthos and cast 18" nova powers every turn, even in assault as nova powers are explicitly allowed to be cast while in combat.

With three ML3 (well, one is ML4) Sorcerers on bikes, you're going to be tossing around a lot of debuffs, you should get at least one with Iron Arm, and as such, should have a unit that can handle anything short of a Seer Council or Screamerstar. What if you come across such units? Well, against a Screamerstar, just send the Nurgle Spawn against them alone and let it tarpit them for a few turns. Against a Seer Council, don't run them all together. Spread out to present a lot of targets and go after the rest of the army. Against a Farsight bomb, hide the Deathstar behind walls and tanks, and then go eat them.

A theoretical list:

Sorcerer, ML3, bike, meltabombs, force axe, Burning Brand of Skalathrax, combi-melta, Sigil of Corruption
Sorcerer, ML3, bike, meltabombs, force axe, combi-melta
10 Cultists, flamer
5 Chaos Space Marines, plasmagun, Rhino, havoc launcher
5 Chaos Space Marines, plasmagun, Rhino, havoc launcher
Heldrake, hades
Heldrake, baleflamer
5 Chaos Spawn, Mark of Nurgle
Vindicator, siege shield
Maulerfiend
Maulerfiend

Sorcerer, ML3, bike, meltabombs, force axe, spell familiar, Last Memory of Uranthos, combi-melta, veterans of the long war
10 Cultists
5 Chaos Spawn, Mark of Nurgle

2,000

As with most things Chaos Space Marine, the list is totally geared towards getting to grips with the enemy quickly. Thus we bring along extra Spawn in case the initial Spawnstar takes too much of a beating early on, the Sorcerers can abandon them for the fresh group. The Maulerfiends could just as easily be Vindicators, but I felt it was useful to have Maulerfiends around in case the Spawnstar needs help out of a jam.

Whatever you support the Spawnstar with needs to be good at killing tanks because you want to be getting the most out of the Sunburst. I kind of feel like a third Drake with a hades might be appropriate in this list just to provide some more anti-air and anti-mech while being hard to take out.

Because the Sorcerers are on bikes, you can exchange the TL bolters for combi-meltas and have that much more anti-tank at your disposal. If all goes according to plan, you have a nearly indestructible unit rushing around blasting half the board every turn with Sunburst. The neat thing about Sunburst is that since it targets everything within the radius, I believe that means you can legally charge anything it hits because the unit targeted it in the shooting phase. The rule isn't 100% clear on that point, however.

With so many high threats rushing across the board, your two Rhinos with lowly CSM's inside should be totally ignored as they go wherever they're needed. And that's usually the point of the whole mess.

Another Idea:

Nurgle Lord w/ Black Mace, Bike, Sigil, Meltabomb, Blight grenades
Khorne Lord w/Axe of Blind Fury, Juggy, Sigil, Meltabomb

1x Nurgle Spawn
1x Regular Spawn
1x Helldrake w/ Bale-flamer
2 or 3x cultists
2x Maulerfiends w/ magmacutters
That brings the total list to more or less 1200 pts... From there you can play with it and either bring Daemon allies, of which i like...
Nurgle herald w/ palequin, FNP Token, greater gift, lesser gift
4 Plague drones w/ Instant Death + Shooty poisoned attacks
1x Plaguebearer
Soul Grinder w/ Phlgem + Slanesh.. Which brings the list to about 1850

Good article Monger