Forsaken.

[Arkiham]

So, I'm planning on building a narrative themed army, which is composed of spawn, forsaken, gigantic chaos spawn, vortex beast (hopefully) , etc.

I want to try keep it around the 2k mark, but the forsaken are 200 points, and I can't see why. Their abilities are random, with a average to hit/to wound.

The only way I can see the justification of the extra points over chaos warriors is the 1/6 chance for 2 damage per hit. But it's rarely going to happen so is that fair? 

 

[DarkBlack]

Forsaken are 20 points more than the same number of chaos warriors. The have the same wounds, save, speed, attacks on average (which are about and (with no banner) effectively the same bravery, but (vitally) don't have the . Not having the mortal wound protection sucks. They were much more appealing when they were core and faster. As far as I could tell, the forsaken's potential has always made them more expensive than they should be.

The mutations are all better that they look on paper; the extra range usually means more models attacking, the rend is good, +1 attack is good and 2 damage is excellent. They worst are the +1 to hit or wound, because those only bring them on par with warriors who are slightly cheaper. They offer some variety, more potential and psychological threat and the 20 points over chaos warriors does not make that much of a difference. I'm very fond of mine, because I got them mainly for fluff and thematic reasons (converted from a box of warriors and the bits left from a spawn kit), but they pull their weight.

TL: DR: I think they should maybe be cheaper, but they are not very much over.

For the record: I run a Tzeentch slaves to darkness with what you describe (basically warriors backed by forsaken, monsters and spawn).

3 points on the rest of that army:

1: Mutalith is regarded as being a bad monster, but that's usually because it's being compared to things that cost 100 of 200 points more. It's a good monster for it's 230 points. Plus it is a fantastic model, loads of fun to build and paint and well designed with the aim of making a centre piece. 

2: Have spawn in reserve, and bring a Tzeentch sorcerer. Bolt of change is at minimum an extra arcane bolt (in matched play), but having a spawn pop up in a unit can be very useful. It occurs anywhere within 3", so is in combat and if placed correctly should survive to have the unit in question still in combat the next turn (i.e. stuck or can't charge). The meanest trick I do with this is to put the spawn on the opposite end to my charge, so the victim has to pile in in 2 directions. Obviously only reliable/effective on big blobs.

3: The army is random and Tzeentch is fickle. So not recommended if you take AoS seriously (i.e. play competitive). Very cool if you're in it for the fun and spectacle; nice and thematic.

[Arkiham]

Yeah i know the vortex is bad but im using it for thematic purposes, something needs to have changed the things into spawns, but the 2 gigantic spawns and the vortex beast it starts adding up so i might not be able to take it.

180+180+240 = 600. awfully expensive, so its kinda optional

i was planning on using the fatesworn warband, and taking the forsaken in a unit of 18 as then i get a ward save on them, - 400

probably a unit of warriors w/halberds again at 18. - 360

some chaos knights unit of 9 - 400

need some chaos spawn - 60 points x as many as possible.

its a really expensive list tbh and makes it completely unviable, its the forsaken which kill it as they arent battleline, if they were it would be great, and i cant see why they couldnt be

[DarkBlack]

The mutalith is good, for it's points. Maybe use mauraders for battleline? 

[Arkiham]

they're really meh as tzeentch. with khorne you can boost their attacks, nurgle their survivability, taking them as battleline would have them serve the only purpose of dying a turn before my more crucial units got into combat an it seems a waste of points as thats kinda what the spawn are there for, 

[Tasman]

^Truth. Marauders really shine with Nurgle or Khorne. When I'm running  Slaanesh, I leave them home and use daemonettes. More points, but they just don't bring enough to the table with that mark. I am finding ways to work them in, so who knows? I did bring them in a Fatesworn battalion and they were not too bad. With mystic shield and sufficient numbers (30) they performed adequately. +1 to hit AND wound stack nicely with the rend they receive from the battalion. With movement 6, at 60 pts, I see no reason to include them, especially in a fluffy list. It's hard for people to say you're running a filthy list when you add in lowly marauders. That attitude with which my opponents usually view them (at first) is one of their greatest benefits. After they get tar pitted and whittled down for a couple of turns, they change their opinions regarding my "elite" marauders.