Set
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Again, not the same thing, but Relics & Rituals had a few 'True Rituals' that worked similarly. (Multiple casters, big effect)
I coulda sworn there was an Incantation in Dragon Magic. It was full of niche stuff (dragon incarnum stuff, new warlock invocations, etc).
I think there was also some Kobold-only ritual thingie in Races of the Dragon (and the web enhancement at the WotC site) that allowed a Kobold to sacrifice a few hit points to gain an SLA or a +1 to Sorcerer casting level...
I *love* the idea of Incantations, and have used it from time to time for stuff I want an NPC to be able to do, but not make available as a spell or magic item effect that the party could easily whip out later.
In my Freeport game, a captured evil Cleric of the Unspeakable One sacrificed an NPC (alas, poor Lucius) to call up some low CR servants of her god to possess a bystander (and the corpse of the sacrifice). As a spell, she would never have been able to do this, but with eight hours, a helper, some Con damage (she had to bleed herself a bit) and a human sacrifice, it was doable. And I never have to worry about the party doing that, because she didn't leave instructions lying around.