slamma wrote:
not really looking to buy anything new, but i am curious if there are new things added since
AoS that become necessary for an army to have (like
BSBs, or an extra sorcerer, or something like that). I'd guess that i could make many warbands out of what i have in my collection and it seems like the whole system is really loose…
what in general works well in game when considering a force? what's something no to leave home without? what kinds of things are considered mean?
To be honest, you can have pretty much anything
If you decide on a 'reasonable' warband - say, a Lord, bunch of maybe 20 Marauders, a core of 10-odd Chaos Warriors, and perhaps 5 Chaos Knights - you are well on your way. If you want to do Archaon and his elite bodyguard, that
ids perfectly reasonable too. You want to do a daemonic invasion of 20 Bloodletters, 10 Flesh Hounds and 6 Bloodcrushers all led by Skarbrand, that is cool too!
The Golden Rule, really, is to make sure your opponent has fun too - if he turns up with a bunch of Halflings, leave Skarbrand at home

On the other hand, if 12 Steam Tanks come rolling across the battlefield, plonk down as many Bloodthirsters as you have!
With that in mind, you really can take pretty much anything you want, so have a think about the kind of theme you want for your army.
There are no essential purchases for that reason. If you are already Khorne heavy, you might want to take a look at the Bloodreavers (think Khorne-specific Marauders who can be _seriously_ pumped up if they are backed by the right units) and Blood Warriors (like your Chaos Warriors but every time one is killed they tend to take down yet more of the enemy!). But they are not essential by any means.
Oh, and once you get a few games in, you will want to check out a few of the new Khorne characters such as the Skullgrinder and Slaughterpriest
* You asked what is considered mean. A good rule of thumb is that if you ever ask yourself whether adding Unit X, Y or Z is too much for the game you are about to play, it probably is

Leave it off the table for that game. I know that might sound a bit bizarre if you are used to points-based games in Fantasy Battle, but you'll soon get into the swing of things - and you can always ask for help or advice here!