1850 Thousand Sons Grand Coven

So with the new "Traitor Legions" 'dex out, I made a 1K Sons list. Points are very tight,  as to get the best stuff (reroll 1s of all saves) you have to take max units.
Anyway,  here is the list I used-

WAR CABAL

Sorcerer- Staff of Arcane Compulsion, ML 2 and MoT

Sorceror- ML 2, Force Axe and MoT
Sorceror- ML 2, Force Axe and MoT
Sorceror- ML 2, Force Axe and MoT

Scarab Occult Terminators- Helfyre Missile Rack
Scarab Occult Terminators- Helfyre Missile Rack
Scarab Occult Terminators- Helfyre Missile Rack

Rubric Squad- Sorceror with Force Sword and Melta Bomb,  Rhino with Havoc Launcher
Rubric Squad- Sorceror with Force Sword and Melta Bomb,  Rhino with Havoc Launcher
Rubric Squad- Sorceror with Force Sword and Melta Bomb

LEGION ARMOURY
Predator-Stock

So I used this list,  knowing it wouldn't be the best, but that it could survive heavy firepower and deliver some damage in return. Between psychic powers, Doombolts and AP3 bolters I thought it would be okay, if not great.
Unfortunately, my opponent brought a very odd and somewhat out of character 30K list.
It was something like this-

Fellblade
Land Raider
Land Raider Proteus
Predator Squadron (with like 4 shots autocannons)
2 Javelins
1 Techmarine and 4 Servitors

The game was basically me hoping to glance with Doombolts or missiles. Got off a nasty deepstrike Doombolt that trashed 2 Predators though. But couldn't take down the Fellblade or Land Raiders. Survived a lot of high S shooting though. The durability of the Scarabs cannot be underestimated.

So how can I improve this list? I wrote a new one that I will throw up a bit later. Any advice is mych appreciated.

Cheers

Throw Magnus in and watch your opponent's face as his 18" D beam trashes his armour.

Count Adhemar wrote:

Throw Magnus in and watch your opponent's face as his 18" D beam trashes his armour.

Yeah,  I live in Australia so unless I sell both my kidneys I'll have to go without the Primarch

Have you tried fully Tzeentch or Heretech disciplines? Tzeentch is better than it seems on paper. I have watched a small tourney where the TS player lost only because he chose not to go with Tzeentch for his last battle.