500 Point Army

[agentindiana]

Here is a 500 point army to go against my friends nurgle chaos space marine army! Tell me what you think as this is my first army ever.

Combined Arms Detachment

Lord Commissar

Basilisk Battery

Veterans
6 lasguns
3 Meltaguns 

Veterans
6 lasguns
3 Meltaguns

Chimerax2

From what I've seen he is bringing a predator tank and some plague marines, but I don't know much else.

[nutty]

It looks like a good start. Vets are solid, and a lord commissar is a nice budget choice.

The basilisk is kind of pricey points-wise.. and might be unwieldy on a small battlefield. But it's a big gun and you can't have enough of those.

[agentindiana]

I might replace it with a leman russ.

[emptyhat]

Taking a Chaos Lord with a mark of nurgle (to get plague marines as troops) and 2 basic units of plague marines to fill up the 1 H.Q and 2 Troops requirement (are you using that?) drains 230 points of his budget for 11 models.
The cheapest Chaos troop choice is the same as a guard platoon squad for 10 far, far squishier models with what are basically las pistols, so that isn't even that much of a saving over the lord+2plaguies option, but if you are playing maelstrom 500 points (which is hilarious on a 6x4 board btw) does start to seem like a better option.

After spending the 230 points I'd be worried that the guard commander might be bringing in 2 leman russ tanks to squash me (which I think you can afford points wise). With plague marines you can't get heavy weapons, just basic imperial special weapons, so you probably need 70 points of rhinos to get in close as fast as possible. You could be looking at a very small army with just the h.q, tranports and as many plague marines in two squads as the remaining points allow. The basilisk might have a lot of trouble accurately hitting those two rhinos as they deliver some pretty mean doom up on your door.

I've found that with 500 points a small number of large blasts have a lot of trouble because of the small unit sizes.

Chimeras are going to be great if you can reduce the chaos marines to infantry travel speeds, so I'd really try and pair them with some lascannons to take out the transports. Meltas will still be the myp when they get to you and you need to take out the last of them, but I doubt they'll have enough firepower to stop an unmolested squad.

Oh, and I'd say that the thing I'd worry most about would be multiple three man squads of chaos terminators deep striking on guard (good luck trying to handle those guys!) the cheapest price for Chaos Termies is just a little lower than 100 points (like a flamer lower). So two of those squads showing up on target at the same time would be pretty nasty. The other thing would be any kind of flyer at this points level. Fitting objective scoring, anti-tank, mobility and anti-air into 500 points (especillay if you are using a classic FoC). I'd recommend a soft ban on flyers and AV14 spamming if you are playing friendlies. Oh, I guess a deamon prince would be pretty hard to stop on this scale too (especially with wings).

TL:DR Basilisk is going to hit hard be be super unreliable and only work while you keep them at range, your short range punch could do with more reliable long range AT options, Chimeras fYEAH!. What about switching the Commissar Lord for a Command Squid with a lascannon?