First, as I said earlier, the mechanics of how this worked are determined by Jim, and he probably worked them out after he finished DM.  So they weren't exactly figured out until after the actual prison was "built" and we are theorizing after the fact, so neither of us are likely to be 100% right or wrong.

That's mean, Serack! Using a Doylist argument in a Watsonian discussion is below the belt! (Please not my tongue is firmly in my cheek).

Lasciel had pretty much zero influence (at least that was described in the books) between Harry erecting the steel ring circle and first using Hellfire in the asault on the blampire lair.

I think (please correct me if I'm wrong) that what you're trying to say here is that cutting of Lash from Lasciel weakened her, and she had to regain her strength before she could influence Harry's senses overtly, and that the amount of Hellfire Harry swings around increases as Lash becomes stronger, giving us a gauge of how strong she is at any given time. The obvious question, of course, is what is Lash using to make herself stronger? I think the only three options are:

1. She becomes stronger as she becomes more familiar with Harry's brain.
2. She becomes stronger as she influences Harry's subconcious.
3. She becomes stronger by tapping into Hellfire, and has to keep the flow slow so as not to fry his brain in the process.

Of the three options, I find option 2 to most aligned with the idea that she can only reveal herself to him after he consciously uses Hellfire. It would make sense that a similar restriction exists on his subconcious, and she's been talking to him, getting him to accept more and more of her help (we know he's kinda a dick, after all, and we know he's been working on turning her at the same time she was working on turning him).

Please let me know if I got your side of the argument right.

If we consider Harry's dream about his father a pertinant source (it's kinda dubious, considering Harry might have just been halucinating), something (Harry presumes "the demon") had crossed some line that allowed Malcolm to speak to Harry.  Implying that until then, Lasciel's shadow couldn't have communicated with Harry without cheating to some degree.  (reference chapter 11 of DB, it's too long to quote)

... I'm not sure the conclusion you're drawing from this evidence makes sense. All we see here is that Lash communicating with Harry "crosses a line" and has consequences. It doesn't say anything about whether the reason she didn't cross the line before was because she didn't have the power to do so (which I think is the point you're trying to make) or because she chose to wait until the optimal time to do so (the argument I'm trying to make). If you believe that Malcolm's appearance is a reaction to Lasciel's actions, then he's there not because she didn't cheat, but rather because she did cheat. I'm sorry, I'm just not following your train of thought here at all. If anything, this evidence supports the idea that she had reasons to choose to wait (Malcolm), rather than the idea that she was helpless to act earlier.

Circles stop powers Inside the circle not outside.

Actually, they work both ways. See Butters vs. Corpsetaker's ghosts, and Harry vs. Binder's Grey Men. Circles are nothing more than Magical Boundaries. They separate Here from There, but don't care whether you perceive Here to be inside or outside the circle.

Harry [...] could take any action he wanted including break the circle and summon the coin.

That is a very good point. Free will, after all, is one of the things we know to break circles. So you're right; the circle was never intended to stop him from summoning the coin, and I was wrong to think that it would hinder him in any way.

Lash whispered to Harry. I have never seen any conclusive proof that Lash was playing along with Harry's expectations about the circle isolating Lasciel.

Lash stopped whispering (well, playing Rock & Roll) as soon as he empowered the circle at the end of Death Masks. She didn't need to stop; it's not like she was inside the circle, after all. If you don't think that was Lash playing along, what exactly do you think happened?

With regards to wether transmitting alone counts for an invasion of the mind, I point towards Summer Knight, and Elaine vs. the Unicorn. All she was doing was transmitting idle thoughts, but it was enough to stop it cold. Anything that's that effective in combat, I think, qualifies as an invasion. So unless someone wants to argue quantity as a qualifier of invasion or not, I would say transmitting breaks the law.

With regards to the WN spoiler, I answer with another spoiler:



-wyl