I really, really liked this rewrite, until I looked over some of the heritages and started to think, "Wow, these are amazing, why would I ever want to multiclass...uh oh."

The Heritages (which I read last mind you.) read crank this class to power level 11. While still now Wizard or Cleric (though not far off in some cases) the balancing factors really go out the window with some of the abilities, especially at lower levels, and the capstones

I mean, at second level +2 defection bonus, AND +2 resistance bonus to saves, that affects allies within 10 feat as well? Why make a Bard who can give +1 (or maybe +2) attack and damage, when I can play this as an angelic style and boost the weak rear end characters, all the while lobbing deadly magical doom.

I do like the separated progressions for Invocations and Blast Shapes/Essences, but I think it should've been six not eight, only because of how precious a resource the invocations are (consider it that each one is like a bonus feat, as extra invocation is one that does something similar.)

I would like to also mention that as this stands now, a Warlock can do crazy damage, way more than any other class by 18th level. Warlock 15/Hellfire Warlock 3. Crucible of Fell power (I think that's the scepter's name, I am doing this on a night without sleep, forgive any failures of context), and the throat slot item from the MiC. Using a full charge from the scepter, add in Hellfire and a triple blast, in one turn you can deal 78d6 (or 78d12 for demonic) up to ten times per scepter and even without that its still 63d6 (or 63d12) which is a massive amount of damage.

This doesn't include chance for missing OR for critical hits. This is literally an average of 278 (or 507 for demonic). I mean...Holy...er Unholy Crap!

I can't really talk to the other mechanics because, well I really like them, I think they all mesh to the flavor you are building well. I just don't know if Warlock is a class that needs a power every single level. I mean, it seems that this build's power takes it to eleven, and the shrugs and writes on a little twelve and sees how much louder it can get!

I will admit I only read down to the demonic heritage, but that one caught my eye as going way over the power scale. I mean, I suppose it has something to do with my DM distrust of Homebrew, and what it does to classes, I mean this is literally tier hopping crazy. Yeah, anyway summarizing time.

I really like what you were going for, but the balance seems to disappear when triple blasting, and the heritages get together to make inane combos.