Regal;
Your suggestions for Pink Coruscation actually nerf it quite a lot, especially the latter - Yes, a single wound for every model under the template with no saves seems powerful, but it also lacks anything that makes it feel especially Tzeentchian. It's basically just a boom gun. Likewise, the latter suggestion is basically useless. Woudns on a 4+ then allows saves as normal? I'd rather use my bolt pistol, thanks. At least that way I ignore 5+ saves.

It took me about two hours to write the first draft, then I've been working on it since, mostly with the help of Raven Angel and Rev. Tiberius Jackhammer over at B&C. This is what the most recent iteration looks like;
Primaris Power: Tzeentch's Warding.
The Sorcerer calls upon his God to favour him in future castings. Blessing. The caster may use his Invulnerable save against the Perils of the Warp, and may reroll one die when determining the effects of any other Power manifested.
Augment: Affect friendly Psykers within 12" by spending an additional Warp Charge.
1:Tzeentch's Firestorm, as Codex.
Augment: Boost to AP3 by spending an additional Warp Charge.
2: Inferno, as Codex.
3: Boon of Mutation, as Codex.
Augment: The caster may roll an additional Reward by spending a second Warp Charge.
4: Doombolt, as Codex.
Augment: Gain Armourbane by spending an additional Warp Charge.
5: The Key.
The Sorcerer reaches out with claws of ether and tears reality asunder, stepping from this world to walk great distances in a single instant. Blessing. Remove the Sorcerer and his unit from the board. Select another place within
3d6 inches on the board and place the models in unit coherency there, without scattering. This counts as moving, and the unit may not move again in this phase. Alternately, this power can be used in the Assault phase, however doing so incurs a Dangerous Terrain check for every model moved.
Augment: By spending an additional Warp Charge, the unit may elect to either) increase its move to 3d6x2 in the Movement phase or) Ignore the Dangerous Terrain check in the assault phase.
6: Pink Coruscation.
Eldritch lightning leaps from the Sorcerer's hand, playing across his foes and destroying them from within. Malediction. Place the small blast marker over an enemy model within 18" and scatter as if for a shooting attack. Any model at least partially under the template must make a Toughness test or lose d3 Toughness for the rest of the game. A model reduced to 0 Toughness or below is removed from play.
Augment: Increase to a Large Blast Marker by spending an additional Warp Charge.