So, Tzeentch has some nasty downsides, but I also feel it didn't capture Tzeentch really.

Current MoTz:
-15% health,
+50-100?% armor regen increase,
-50% armor regen delay.

Proposal:
-25% health
+15% armor (all is dust...)
-50% armor regen delay, +25% armor regen rate

Then, Boon of Change: becomes Shroud of Change, target 1 ally, he becomes Shrouded, break out the buffs:
-50% ranged/DoT damage,
and his armor regenerates whilst taking damage, this rate increases for his "- armor regen delay", "+ armor regen rate" bonus etc. (So Slaanesh would have slower armor regen from this spell than normal),
+30 AP to his ranged attacks.

To still get 'heal' XP, could grant a low normal healing effect, say 1/4th of Warp Regeneration; or it could start healing once armor is full/there is no armor to heal (to allow reviving with this spell & still healing too).

Nurgle & Slaanesh have AoE effects; Nurgle, loving caring father, Slaanesh the group .. behavior..
give Tzeentch, fickle god etc, the best & most unique single-target buff.
+30 AP: 'Tzeentch infernus bolts or whatever. Note: only a bonus if the wielder hits, something with a Toughness value higher than his weapon. If he hits someone with +30 Toughness over his weapon (100 AP bolter vs someone with Relic armor..), it is approx. a +15% damage bonus. i.e.: NOT gamebreaking. It wouldn't buff things like Lascannon/Meltagun... ; mostly regular bolters, and depending on enemy Toughness, Plasma weapons.
-50% ranged/DoT damage: big buff.. Apothecary survival vial gives 30% damage reduction, works vs melee. The Eldar one is AoE,.. the Shroud effect would be only active on the last buffed player, except the armor/heal effect.
Or, perhaps reduce the effect to -30% (still only vs ranged & DoT), make it a cast spell with a high cost to reduce spamming.


Chances of such changes happening are minute at this point, I know.
Still, this is something I wanted to propose for discussion.

No , it's stupidly OP

Absolutely not, and did you fail basic math? the 15% hit to health (30 hp) is bad enough, especially for sorcerors, who get only 75 armor. 90 with the red armor, which means for losing even MORE health (60 fucking hp, leaving you with only 140, and cqc bolter does 42) you get a piddling 11.25 armor with a base of 75, or 13.5 armor with Warp-forged armor. 5-6 bolter shots and you are fucking dead. So you are dead in about 1.5 seconds, given the bolter's RoF.

Numbers can be tweaked;
give the sorc less health, but equivalent armor to a normal marine for example.

Boon of Change should act like a Medicae-Grenade that disspipates instantly.
That would solve the Problem Tzeentch Sorcs face as they can't really get into the action to do their job with boon of change.

Let it be something throwable, keep to slow heal over time it has now, maybe up the Warpcharge-cost a little and we would be good to go

The only Dust Mrines are Thousand Sons, since it's not a Tzeench follower thing, but was in fact caused by the Rubric of Ahriman.