Whereas I would probably allow it, because allowing would (IMO) have more potential for both fun and story. If it is really, really important that the party not get the answers they are after, Sharzzakhar prevaricates until rescued. Dragons (well, maybe not the blue ones) are known for being loquacious, after all. If you don't want the trap to work, maybe the Great Mother was growing tired of her consort anyway and is glad to be rid of him. Of course there must (may) be a token effort to rescue him (e.g. another half-dozen fiendish vampiric blue dragons). For me, plot is there to give the pcs something to bend to suit themselves. That's where my fun is.MerakSpielman said:I'd use the criteria that if the caster knows in advance exactly which being he wants to summon, the being gets a choice. There is a good reason for this. If your wizard wants to gate in a fiendish, vampiric ancient blue dragon, chances are he just wants some help during a nasty combat. However, if he wants to Gate in Sharzzakhar specifically, chances are he's doing so for a specific plot reason, perhaps as part of setting a trap for the Great Mother dragon, or to ask specific questions the answeres to which only Sharzzakhar knows. Not allowing the Gating of specific indivuals helps the DM maintain a bit more control over the plot, especially if it's centered on the political machinations between groups of outsiders (as I believe PC's game is at the moment).
Or, hey, maybe she just gates him back.
But that is just that example. I personally like the idea of calling specific individuals, even powerful ones. I do not believe that advancement, templates, or class levels necessarily make something unique. That is a decision to be made on a case by case basis, I think. I would tend to give the status 'unique individual' only to creatures built as such, all members of every class of one.
For the example of 'King Skyfire' above, for me it comes down more or less exactly as coyote 6 said. If it is just a tough balor that happens to be a little more powerful, a little different from the norm, no choice about gating. If it is merely that a balor's stats were used as the basis for this creature, it is probably unique.
I certainly do not, however, have any immutable guidelines for deciding what is a unique reature and what is not. As another example, in my primary campaign setting the term 'Gloom' describes a large class of epic monsters, each of which is also a unique creature.
If the description in your head is 'advanced this', 'templated that' or 'X with Y levels of Z' it is almost always not a unique creature (single member of a class of creatures). If the players want to summon one they have to stat it up themselves, preferably beforehand. I decide if it exists, if it needs to be modified, and if it happens to be unique. Of course.
Has that, in any way, even touched on the question at hand? Unlikely. *shrug*