Now that I've had time to look over the new CSM book and play some games with the army, I wanted to post some thoughts on it as a whole as well as what units I think are clear winners and losers and how I see Thousand Son armies being built in 6th. This is going to be part 1 of a series that deals with Thousand sons and will primarily be my introduction on what I think of how the CSM book handled Tzeench/Thousand Sons in general.
With that said, overall, the codex feels like a let-down. Things that I wanted to see (and I imagine other fans of the army wanted to see) were not introduced into the codex and the units that were included in the codex are underwhelming. Specifically, certain older units were not changed in a meaningful way to give them a competitive edge (like Raptors or Possessed) while some of the newer units are not going to see the light of day in any respectable tournament lists (Maulers or Warp Talons). In short, the codex has a lot of cool units that people want to take but will be punished for taking them by the more main-stream armies like IG, Necrons, GK and SW.
I would have liked to see rules or options to actually field legion specific armies rather than just the "take the mark, get a minor benefit" treatment that everything outside of the four Cult units received. It would not have been that hard to give a Terminator upgrade to the Cult units so that you have Cult rules/units in terminator armor which allow players to get a meaningful and potent elites choice. Taking Terminators with the Mark of Tzeench is not the same as having Thousand Son Terminators and as it stands, the current CSM Terminators are very bland and are not that great. Conversely, it would have been very easy to copy/paste cult upgrades/rules with modified points limits to any other unit entry such as Bikes and vehicles even. So all in all, a big disappointment on the treatment GW gave the Legions in this codex.
On Cult units:
I also think that the codex fails to give some of the Cult units justice. Nurgle and Slaanesh came out alright with not only a slew of nifty rules but great wargear to match. Khorne has decent rules and upgrades but has to pay a bit more than is worthwhile for them and they really should have had fleet since they are an assault based unit and NEEDS to have a more reliable way to get into combat since Rhinos are not assault vehicles and Land Raiders are not the best thing to use to deliver them. Then we have Thousand Sons... I strongly feel that Tousand Sons and Tzeench in general got the short-end of the stick this codex. This leads me to believe that there is just a lack of understanding or interest in Tzeench/Thousand Sons in GW staff at the moment.
Regarding Thousand Sons, specifically:
Rather than merely complain, here are some changes I read about on Dakka by GameFreak975 that I think would make Thousand Sons more viable...Below is a direct quote:
So I was really bothered when Ahriman first came out in October. Don't get me wrong, I love having Mastery Level 4 but he feels hampered at the same time that he feels powerful. He is the arch-psyker of 40k and he HAS to generate a power from Tzeentch? Can't choose Divination? Real master of the warp there. But anyway, here are my ideas for Ahriman and the Thousand Sons elite entry.
Ahriman - 250 points
WS 5 / BS 5 / S 4 / T 4 / w 3 / I 5 / A 3 / Ld 10 / Sv 3++
Unit Type: Independent Character
- The Black Staff of Ahriman
- Frag and krak grenades
- Bolt pistol
- Mark of Tzeentch (Same as Codex: CSM)
- Sigil of Corruption (Same as Codex: CSM)
- The Pendant of Ohrmuzd
- Inferno Bolts
- Psyker (Mastery Level 4)
- Guarded by Fate
- Master of Deception
- Veterans of the Long War
The Black Staff of Ahriman: Allows Ahriman to cast up to three witchfire powers per turn (provided he has enough warp charge). In addition, if he fails to cast a witchfire power he may attempt to use the same power again if he so desires.
Range - / S +2 / AP 4 / Melee, Concussive, Force
The Pendant of Ohrmuzd: Counts as a Spell Familiar (Codex: Chaos Space Marines).
Guarded by Fate: Ahriman may use his invulnerable save against wounds caused by Perils of the Warp, but the power of the Warp is such that successful invulnerable saves must be rerolled. In addition, any wargear or special rule that would otherwise negate Ahriman's psychic powers on a flat D6 roll only functions on a roll of a 6.
Master of Deception: Nominate up to D3 Infantry units in your army before deployment. They gain the Infiltrate USR.
Psyker (Mastery Level 4): Ahriman may generate his psychic powers from the Tzeentch, Biomancy, Divination, Pyromancy, Telekinesis, or Telepathy disciplines.Master of the Rubricae: In a primary detachment that includes Ahriman, Thousand Sons are Troop choices.______________________________
Thousand Sons - 150 points
Unit Composition: 4 Thousand Sons, 1 Aspiring Sorcerer
Thousand Sons: WS 4 / BS 4 / S 4 / T 4 / W 1 / I 4 / A 1 / Ld 10 / Sv 3+
Aspiring Sorcerer: WS 4 / BS 4 / S 4 / T 4 / W  / I 4 / A 2 / Ld 10 / Sv 3+
Unit Type: Infantry, Sorcerer is Infantry (Ch)
- Power Armour
- Boltgun (Thousand Sons only)
- Bolt pistol (Aspiring Sorcerer only)
- Force Weapon (Aspiring Sorcerer only)
- Aura of Dark Glory (same as Codex: CSM)
- Mark of Tzeentch (same as Codex: CSM)
- Inferno Bolts
- Slow and Purposeful (Thousand Sons only)
- The Sorcerer Commands (Aspiring Sorcerer only)
- Psyker (Mastery Level 1) (Aspiring Sorcerer only)
- Veterans of the Long War
Inferno Bolts: Any shots fired from boltguns, bolt pistols or heavy bolters are resolved at AP3. In addition, Inferno Bolts have the Soul Blaze USR.
The Sorcerer Commands: When the squad is led by a character with the Mark of Tzeentch, the Thousand Sons no longer count as Slow and Purposful and instead gain the Relentless USR.
For every 9 models in the unit, one Thousand Son may replace his boltgun with a heavy bolter for ... 10 points
The Aspiring Sorcerer may increase his Mastery Level by 1 for ... 25 points
The Aspiring Sorcerer must generate one power from Tzeentch and then may generate an additional power from the Divination, Biomancy, Pyromancy or Telepathy disciplines (provided he has enough mastery level to do so).All other options remain the same in point cost and availability as in Codex: Chaos Space Marines."
Well, that concludes part 1 and my gripe with how Thousand Sons were portrayed in the codex. Next up is a more specific overview of individual units, followed by more content that will deal with Thousand Son army lists and what we have to work with as Thousand Son players.