I tend to agree. I also think this is what I was trying to say and what Mouseferatu said a little better in terms of adventure design.Now once before the final battle may be ok, but many continued times of BBEG teleporting away to safety in the nick of time cheeses me off. Don't even put BBEG there if he is just going to run away. Leave any message from him in some other manner.
During most games, I think these sorts of things happen. The players may encounter teleporting (or other) effects, even in combat, that don't follow the rules of any published ritual or power. Encounters with the strange and unusual are a cornerstone of the exploration parts of the game. Nobody playing the game, either players or DM, should expect that every strange effect is modeled by an existing rule, and neither should they expect that only effects that exist in the published rules should appear.So IF there is not during combat a chance for BBEG to teleport away without using the teleport rules: LOS, etc, then the players should have options also to be able to violate those rules when not in combat as well.
The dividing line here is, in today's gaming jargon, who has narrative control over these sort of non-rules-arbitrated effects. In a game like D&D, it's problematic to give players unlimited control over these sorts of things. Most adventures are presented as a series of problems or obstacles, and giving players unlimited control of the plot usually does not lead to a satisfying resolution. (Although DMG p. 28 gives a counter-example where it does.) Giving the DM control of these things is, I've always thought, one of the assumed rules of the game, and I'm a little disappointed that the 4e DMG doesn't directly address it. As Mouseferatu mentioned though, the DM using his narrative control to make the obstacles of the adventure insurmountable is not good adventure design either.
I agree with the principle here, if not the details. To me the key is not "consistency" precisely, but believability. It's believable that a demon lord would have a way to move around his realms, beyond his listed teleportation speed. In fact, it's unbelievable that he does not, which is what sparked this whole thing.Consistency is important to me during the game from both perspectives. When something seems to violate known concept, and answer is needed as to why. That reason being so BBEG can just get away "this time" isn't always enough and sometimes offensive. So the DM needs to use caution when breaking from standard conventions.
I'm not a fan of the attitude that if an enemy can do it, so should the players be able to. I agree with the posters who have said that 3e tended to foster such an attitude, and that 4e was right to attempt to dispel it. The players should not be able to do everything that the monsters can. As an example in the RAW, there's several enemies that can dominate their foes (as in inflict the "dominated" condition), and yet no player power to do so. Is this a problem?
You say that you have trouble coming up with a spell or ritual to have Graz'zt teleport away as the adventure demands. May I suggest that you simply treat it as if that were one of his listed powers? Perhaps even insert it into his statblock:
There, is that an unbelievable power for a demon lord to have? Is it inconsistent, aside from with his published stat block?Infernal Escape (standard, when Graz'zt is in mortal peril but the DM wants him to live, and when the PCs have not invested enough in negating this power; encounter) Teleportation
Graz'zt teleports to anywhere within his domain.