Okay, so I'm doing a bit of a theoretical deep dive and examination of several of the "worthless" or 'not usable' units in the Chaos Space Marine Codexes. So first I'm going to post my take and analysis of the unit in question, and then I'd like feed on the unit and my analysis. Not keep in mind I avoid tournaments like a combination of a clingy X-girl friend combined with the black plague I try to play friendly games. That being said tournaments in this area have an absolute stranglehold so I can't avoid the effect of tournaments (IE the highly competitive atmosphere and the min-maxing list building approach). So it's a bit like doing recreational boxing against Muhammad Ali. Even if he's got both legs and arm tied behind his back and his eye covered, he still knocks you all around the ring and then looks at you with this look that says "Why aren't you trying?"
So, first unit I want to look at: Thousand Sons.
You can also see my analysis of the following units:
Khorne Berzerkers 
So 150 points for 4 Thousand Sons with an Aspiring Sorcerer. For that 150 points you get a slightly better then standard Space Marine stat-line, the advantage going to the Thousand Sons LD10 base. Beyond the stat line you get a rather lengthy list of special rules for the unit.
The Sorcerer is bound with the Champions of Chaos (CoC) Special rule, while the entire unit is fearless. The unit automatically has Veterans of the Long War (
VotLW), so they have Hatred (Space Marines) which while this sounds nice at first glance, we'll be coming back to it. The unit also have Mark of Tzeentch which gives them a +1 to their Invulnerable save, which when combined with the Aura of Dark Glory wargear that comes with the unit gives them a rather beefy 4+ invulnerable save.
The Sorcerer get a Force Weapon and is a Level 1 psyker. Okay that's note worthy on it's own.
Okay, so 150 points for 5 wounds with a 3+/4++ save. Not exactly horrible. For comparison, 150 points will also get you a 9 Man unit of normal Chaos Marines with an aspiring Champion that has a power weapon and melta bombs while the marines get a bolt pistol and
CC weapon, giving them 3 attacks on the charge and 2 if caught flat footed. 5 wounds with a 4++ and a force weapon compared to 9 wounds with a power weapon. It should be noted that the 9
CSMs with that configuration actually come in at 3 points less then the 5 Thousand Sons.
Now for that 150 points the Thousand Sons also get inferno bolts, making their bolters AP3. Okay, that's a nice little marine killer.
However, the unit has some major and unavoidable downsides. The most obvious is it's limited with the Slow And Purposeful special rule, meaning the unit can not run, sweeping advance or fire over watch. Keep these points in mind. I'll be coming back to them.
Less obvious as a limit is the Aspiring Sorceror and his mark of Tzeentch. See Psykers with a Mark of Chaos
MUST roll at least once on their patron Gods table. Okay, so he has Mastery Level 1, which means he has to generate his single Psychic power from the Discipline of Tzeentch. Now granted, thanks to Psychic focus he automatically gets the primaris power so he can wind up with 3 powers in total (Force, the Primaris plus the one he generates from the table). Okay, how bad can that be?
Well there's the primaris power, Tzeentch's FireStorm, which is a range 24" random strength between 2 and 7 no
Ap blast assault attack that has the chance to inflict a further D3 Strength 3 no
AP hits.
-Okay. kind of wonky. But not something I would be under the heading of "Get a kick in the balls". The Random strength is what hurts it as does the lack of any
AP.
the 1-2 Result is Boon of mutation, which is a 2" blessing that in theory gives a roll on the Chaos Boon table. To take that test the targeted character must take a S4 no
AP hit and survive.
-um... okay. So on it's own you would have to target the Aspiring Sorcerer himself. Otherwise you have to have an Independent Character, with the Mark of Tzeentch join the unit, or otherwise be right next to the Sorcerer while being less then 2" but more then 1" from the squad. yeah... The Boon table is so incredibly hit or miss already that stacking rolls on it just takes 'random' and... well keeps it random.
the 3-4 result is Doom Bolt. a Range 18, S8
AP 1 beam attack that if it causing a vehicle to explode then you roll
2D6 for the range of the explosion.
- okay. an 18" armor killer. That's nice. the Detonate is kind of 'meh' over all since most real threat vehicles are armor 13 so you'd need a 5 to penetrate, and then a 5 to explode it and then get to roll to see how big of an explosion, which on average is going to be 7". Overall good for Rhino Popping before charging what ever chewy morsels were inside it.
the 5-6 result is Breath of Chaos, a 2 charge Template S1 AP2 poisoned (4+) witch fire. Well it's poisoned, so it's going to wound anyone on a 4+, and it's an AP2 so anything that doesn't have an invul save is goign to be hurting. It does have a nice bonus in that if used against a vehicle, it automatically inflicts a glancing hit on a 4+.
- okay, over all not exactly bad. It's not going to be taking out Land Raiders on it's own.
So of the 4 options the Aspiring Sorcerer has from the Tzeentch table, it's Primaris power is "ok" the 1-2 is rather underwhelming and I would just swap it for the Primaris anyway. The 3-4 is the 'want' power from the table, while the Breath of Chaos is... well it's interesting but honestly it seems like something better suited to Nurgle then Tzeentch.
Do they have any other downsides? Yeah, they do. Firstly they have no options to really speak of outside adding more Thousand Sons to the unit. And at that they are 23 points each. Yes the Aspiring Sorcerer can take melta bombs and boon of mutation. Yeah, Boon of Mutation has the same problem as Boon of Mutation Psychic power.
Okay, so how do they really stand up on the battlefield?
Well, the best way I can describe them is to say they are somewhere between a lame shield and a glass sword. When they hit hard, they do a lot of damage that most units can not walk off. They are still space marines meaning they shoot their targets on a 3 or better, so one average you're going to land 2 out of every 3 shots you make with them. Nice. They have S4 AP3 bolters. So against most marine forces you'll be wounding on 4+ and most of the time normal marines either won't have an invulnerable save or will be forced to take their cover saves. So I did some numbers grinding and figured that a 10 man Thousand Sons unit, rapid firing at a 10 man Tacticle squad of Space Marines will average out to 7 wounds per round of shooting.
So the upside of that scenario: those marines you wounded, don't get their armor save. Oh, and chances are good that you will be able to charge them and finish off the remains of the squad.
The downside of the scenario: it's very optimistic and in a vacuum. The other problem with the scenario, that 10 man Thousand Sons unit is going to run you 265 points, compared to the 10 Tactical marines that with a melta gun run a more budget friendly 150 points. So while it's a semi-safe bet that your 10 man unit is going to wipe out their 10 man unit, realize that you've only made back 150 of your 265 points. You're still coming up a rather painful 115 point short. And that's assuming that the 265 points worth of Thousand Sons get to engagement with that Tactical squad unharmed. Considering that 265 points is more then 1/10th of a 2500 point army list, that's leaving you at a sizable disadvantage that's only going to get bigger the more points you put into that unit. Want to give them a Transport? Well now you're looking at 300 points for the unit. Want to go with a Max-sized unit for maximum fire power ability? 500 points before you add a transport of any kind.
So the strengths of the unit are definitely their short ranged fire power ability coupled with their 4++.
The Downsides of the unit... that is a longer list. The Aspiring Sorcerer, the Slow and Purposeful, the lack of reliable armor beating abilities, and their painful price tag.
Anyone have any additional info to bring up or alternative views on Thousand Sons?
I am changed . . . an outcast now. 
