I've been thinking about epic spells, and I've come to the conclusion that it is not a good idea to let Mostin develop the perceptual transcendence sequence of spells.
This is an interesting observation - I was in two minds myself about okaying it. They are kind of uber-munchkin. I guess it comes down to the way the DM exercises control in the game, and the way the characters interact.
Philosophically, I tend to prefer plot-driven constraints/controls upon characters, as opposed to mechanical ones, or ones which depend upon DM fiat. And Mostin's rite was designed as a means to interpret the
web of motes - not to exercise huge magical power. It simply happened that, mechanically, it also makes his spells almost irresistible.
Nwm's caveat - that it should only be used for divination - works in two ways. First, it conveys the fact that Nwm himself is
very nervous about participating in a series of spells which empower three already very dangerous arcanists yet further. It places a kind of moral responsibility upon those involved - which I feel is no bad thing (it's an epic campaign, after all). But it's also a recognition that the mechanics are merely there to explain something that happens in game - they have no real value in and of themself. Dave is very good at not getting sucked into a mechanistic mind-set when he plays.
But even if Mostin had - for example - gone power-mad, what could he do? Translate to Afqithan and kill Ainhorr? Translate to Azzagrat and attempt to kill Graz'zt? (Defeat
mind blank, penetrate anti-teleportation wards, hope that the Prince isn't in his sanctum, and overcome Graz'zt's SR) Attempt to
Gate Graz'zt (who may decide not to come), and then hit him with a
disintegrate? Of course, there is nothing that Mostin can do
in Wyre itself, without the implicit say-so of the Claviger (another plot driven control, btw.)
The characters' actions do not exist in a void. If Mostin alone were to eliminate Ainhorr, how would Graz'zt react? How would his strategy change? What other powerful entities would suddenly become interested? How would Soneillon react to Mostin and subsequently view him?
A more long-term concern might be about setting a precedent for the mechanics of epic spells - what is allowable, and what is not. This I will continue to judge on a case-by-case basis - given the context that they are to be used in, and the purpose that they serve.
I guess I feel there are more ways of limiting player choices - when necessary - than just saying 'no.' Don't get me wrong, I have said a flat 'no' to several epic spells that Mostin's player has proposed - sometimes you
do have to. But this one is so specific - it requires these four casters knowing these four spells, and sufficient buffing and recuperative magic and 9th/epic level slots available. And all being willing to participate.
Still, the spell sequence
does have very big plot development consequences. And nothing that I'd foreseen, either. I like it when that happens.