Mind Spike seems to be an ability only used during Shadowform. Using it in Voidform doesn't make that much sense unless your target would die.
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I'm not even using StM and I'd still say your arguments are pretty... questionable.
DoT weaving in Voidform? Yeah when you have some long living adds. If not you would NEVER cast a DoT in Voidform. That's the whole system around Void Bolt and Void Form. Cast your DoTs outside of Voidform, go into Voidform and don't bother with DoTs anymore, just deal damage.
And there is a difference between "king of mass AoE" and "acceptable AoE at all". Shadow Priests damage outside of Voidform is pretty bad, AoE is pretty bad outside and inside of Voidform. Why make it worse with the changes to Void Bolt? It doesn't make any sense, does it?
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The time until you enter the first Voidform as a Shadow Priest is so ridiculous, your damage is non-existant, you're slow and useless. The ramp up time is too high. We once had a talent that gave us 100 Insanity at once - what happened to it?