Well from the top, it looks like some of your points and math was a bit off. Here's what I get from the list you posted, think it's right:
L: Demon Prince -
MoN, tendril, level 2 = 470
H: Festus the Leechlord = 185
H: Sorcerer -
MoN, level 2, demonic mount = 190
H: Sorcerer -
MoN, level 2 = 140
C: 12 Warriors -
MoN, full command, shields = 252
C: 12 Warriors -
MoN, full command, shields = 252
C: 16 Marauders -
MoN, standard, champ, flails = 126
C: 5 Marauder Horsemen -
MoN, standard, champ, spears = 124
C: 5 Marauder Horsemen -
MoN, standard, champ, spears = 124
S: 3 Ogres -
MoN, full command, ahw, chaos armor = 215
S: 3 Ogres -
MoN, full command, ahw, chaos armor = 215
Total: 2293 points
So that's 43 points over to start with. Luckily you've spent a LOT more points than you want to on command options - how many points did you give away for all those standards on units without the punch or numbers to support them? Let's clean the commands up:
L: Demon Prince -
MoN, tendril, level 2 = 470
H: Festus the Leechlord = 185
H: Sorcerer -
MoN, level 2, demonic mount = 190
H: Sorcerer -
MoN, level 2 = 140
C: 12 Warriors -
MoN, full command, shields = 252
C: 12 Warriors -
MoN, full command, shields = 252
C: 16 Marauders -
MoN, full command, flails = 130
C: 5 Marauder Horsemen -
MoN, musician, spears = 106
C: 5 Marauder Horsemen -
MoN, musician, spears = 106
S: 3 Ogres -
MoN, musician, ahw, chaos armor = 175
S: 3 Ogres -
MoN, musician, ahw, chaos armor = 175
Total: 2181 points
Now we've got 69 points to spend
. If you're curious on the choices I made feel free to ask, but this is the more standard command choices you see on the table - and I also like musicians, so everybody gets one. Next up is the list with my changes that don't mess with the models involved:
L: Demon Prince -
MoN, tendril, level 2 = 470
H: Festus the Leechlord = 185
H: Sorcerer -
MoN, level 2, necrotic phylactery, chaos steed = 166
H: Sorcerer -
MoN, level 2 = 140
C: 12 Warriors -
MoN, full command, shields = 252
C: 12 Warriors -
MoN, full command, shields = 252
C: 20 Marauders -
MoN, full command, flails = 150
C: 5 Marauder Horsemen -
MoN, musician, spears, light armor = 111
C: 5 Marauder Horsemen -
MoN, musician, spears, light armor = 111
C: 5 Warhounds = 30
C: 5 Warhounds = 30
S: 3 Ogres -
MoN, musician, ahw, chaos armor = 175
S: 3 Ogres -
MoN, musician, ahw, chaos armor = 175
Total: 2247 points
I downgraded the sorcerer to a steed (he didn't need the demo-horse's M8 but he could use the 2+ save) and gave him a cheapo 10 point item that could come in handy, boosted the marauders to a healthy 20 for full
CR, gave the horsemen armor for a 5+ total save, and popped in the warhounds that Metsuri mentioned. Ultra-useful pups, them. Besides the excess command models you had, this list doesn't involve really changing any models, besides adding the warhounds. I think it addresses some of the problems that Metsuri brings up, but you still aren't going to be able to charge across the table and tear their face off. BUT I don't think that's your point - you're here to magic them to hell with the killer nurgle lore.
FWIW I like that you've taken the prince, the spear horsemen and the ogres - particularly the prince and ogres, lots of modeling opportunities and not units you see too often.
From here your next choice is to drop the prince and recycle his points into 'better' things. Gear for the sorcerers, more warriors for those 2 shrimpy 12-man units, possibly a unit of nurgle knights to ram down their throats. I'd be curious how a revamped prince list runs though, I think it's got possibilities.
- Salvage