>We killed every dragon with our group before trying. I saw
>no benefit whatsoever to doing so.

It's reasonably subtle, but having tried it both ways in testing, I'm just telling you what I'd do if I were doing it.

>This me be an oversight
>but the essences can be dispelled.

Not an oversight.

> About the only advantage
>was that it gave me a better idea of what to expect; however,
>I still think Tiamat is a bit over the top.

She IS tough. :)