allright, let's start at the top
Daemon Prince:
Firstly, a daemon prince is always a solid choice for you'r
HQ option. What he lack's though, is mobility. A problem easily fixed with a pair of wings, highly recomendeable.
secondly, bolt of change is not a very good option. he's not gonna win his fights shooting anyway, so a better power would be Warptime, which boosts his close combat effectiveness tremendeously. i would recommend it over Bolt of change any day.
Chaos lord:
Not a very used
HQ choice, but i personally always like seeing him out there, and with a couple of termonators as a bodyguard, he's quite the hard hitter. i would drop the
MoK combination with the daemonweapon, because those ones WILL come, and when they do it hurts. rather, the +1
str. of a daemon weapon of undivided, the poison weapon of nurgle, or the instagib of slaneesh are all okay options in comparison.
Terminators:
Here i would recommend dropping one terminator, and getting a landraider. they'll be too slow otherwise. with 4 termies, there's room for the lord too. oh, and a heavy flamer beats the reaper at close encounters, so i would go with that instead.
Possessed:
many say that these are not worth taking. i personally run 10 with a
MoT, on foot. if you do take them, i would recommend either
MoT or
MoN for the added durability, as they are expensive, and deserve the protection if footslogging.
Chaos Dreadnaught:
an okay choice, don't personally use one, due to the firering frenzy, but can't fault others for doing so.
Chaos Marines:
Specialize these. use two sets of special weapons, and save the heavy weapons for the Havocs. they'll do one job 10x better (flamers, plasma or meltas) than a dual role of mix n' match. an
IoCG is a solid choice on these. also, Rhino's make their day so much better. see the berzerkers for why.
Plague maries:
again, specialization. don't mix it up, pick one and roll with it.
Berzerkers:
Can't fault these, they're good, although the meltabomb is quite redundant when you have
str. 5 against rear armour anyways. i assume the rhino is going on these guys? they will definitely need it the most, as they'll otherwise be splattered all over the pavement long before reaching the enemy.
Spawn:
arguably the worst unit in the entire game. i would drop these entirely, and use the extra points elsewhere....
Blight drones:
never used these myself, so can't really give any advice here.
Obliterators:
always good. definitely keep these bad boys, they'll always earn their keep.
Vindicator:
the vindicator is nice, but I would drop the combi weapon, as it's main gun is an ordnance weapon, and can thus not be fired at the same time as any other weaponry.
hope it helped a little