So I have put together three lists that use/contain certain models which I either already own, or have conversions in mind for. One or two of the conversions are fairly fluid (eg. I have a tank conversion in mind that could end up being one of a number of tanks).
Pretty much just curious what people think, whether any of these lists seems particularly good/bad/terrible/fun. (To me they all seem pretty fun and varied on paper, but might be boring to play for some reason I'm not considering.)
I'll try and shorthand the lists as much as I can, while still trying to be clear as to what they contain.
LIST 1 - SPARTAAAN! (2004 points)
Spartan Assault Tank - 2x Quad Lascannons, Twin Heavy Bolter, Havoc Launcher
Carrying:
- Three Plague Marine Squads of 7 (Plaguesword + Plasma Gun, 2x Blight Launcher + Knife, 2x Flail of Corruption + Knife, 2x Boltgun + Knife)
- Chaos Lord - Combi-Plasma, Balesword
- Malignant Plaguecaster - Corrupted Staff, Blades of Putrefaction, Miasma of Pestilence
- Malignant Plaguecaster - Corrupted Staff, Putrescent Vitality, Miasma of Pestilence
- Foul Blightspawn
Daemon Prince of Nurgle with Wings - Malefic Talons, Hellforged Sword, Plague Spewer
Cultists x 10 - All Autoguns
Cultists x 10 - All Autoguns
Cultists x 10 - All Autoguns
Giant Chaos Spawn (of Nurgle)
Maulerfiend - Maulerfiend Fists, Lasher Tendrils
Spartan, Prince, Giant Spawn and Maulerfiend head up the board, dropping off squads of plague marines as and when needed. Cultists bring up the rear, and sit on objectives. Organised correctly this gets me two Battallions, so 10CP from detachments. Not a lot of targets, but they're pretty strong, and getting first turn would be very handy. Spartan get get into combat and still fire all weapons and fallback / charge without being tarpitted.
LIST 2 - THE SMALLER TANKS OPTION (2018 points)
Daemon Prince of Nurgle with Wings - Malefic Talons, Hellforged Sword, Plague Spewer
Chaos Lord Terminator - Combi-Plasma, Balesword
Sorcerer Terminator - Combi-Plasma, Balesword, Putrescent Vitality, Miasma of Pestilence
Blightlord Terminators x5 - 3x Combi-Plasma, Blight Launcher, Flail of Corruption, 4x Bubotic Axe
Plague Marines x 7 (Plaguesword + Plasma Gun, 2x Blight Launcher + Knife, 2x Flail of Corruption + Knife, 2x Boltgun + Knife)
Chaos Rhino - 2xCombi-Bolter, Havoc Launcher
Plague Marines x 7 (Plaguesword + Plasma Gun, 2x Blight Launcher + Knife, 2x Flail of Corruption + Knife, 2x Boltgun + Knife)
Chaos Rhino - 2xCombi-Bolter, Havoc Launcher
Cultists x 10 - All Autoguns
Giant Chaos Spawn (of Nurgle)
Maulerfiend - Maulerfiend Fists, Lasher Tendrils
Hellforged Contemptor - Chainclaw x2, Soulburner x2
Hellforged Predator - Infernal Flamestorm Cannon, 2 x Heavy Flamers, Havoc Launcher, Infernal hunger
So here, my custom tank conversion is instead a melee-based predator (weird, I know, but the model would look cool). The Lord and Sorcerer would stay in orbit with the Blightlords, all ready to drop in when needed with lots of plasma shots (with rerolls on 1's). The sorcerer can give them -1 to hit and +1 toughness to try and keep them alive for a couple turns. Tanks and maulerfiend/spawn do the usual aggressive negotiations. Contempter joins them this time, being able to move and advance and still pump out the soulburner shots without any hit penalties. Shame that the predator can get tarpitted, but it gets a fair few attacks (especially if it charges) and it'll have a decent amount of backup.
This list gets me a Battallion and a Vanguard, so only 6
CP from detachments. Also too many points, but I can drop 18 points easily, I just haven't refined the details yet.
LIST 3 - THE FOOTSLOG LIST (1998 Points)
This list is identical to list 2, except I have removed the two Rhinos (I don't own rhinos and find the models a little boring haha), and replaced them with either another Giant Chaos Spawn or maybe a dual-Butcher Cannon Decimator or another Contemptor.
Just means much the same attack as in List 2, but the with a much stronger holding of backfield objectives with plague marines on foot. Though I could also do this with the rhinos acting as walls. But then, I could also patrol the back field with my two giant spawn.
I'd be interested to hear any feedback

It's a little messy I know but I hope I've not made too terrible a set of list options to play around with.
Edit - I'm aware that the Giant Spawn would break detachments for Legion Traits, but I'd either put it into a detachment where the trait didn't matter or I'd just plan to summon them instead of starting them on the field.