Funny thing, Orpheus sometimes uses a tadpole, and sometimes doesn't. If you accept the final tadpole from the emperor, but then instead of transforming, you force him to leave, Orpheus is going to use that tadpole. But if you never accept the tadpole from the emperor, Orpheus is going to turn into a mind flayer without the tadpole (since you don't have any). And there is no explanation provided.
Ah, so that's what it is. I was defying the Emperor at every turn in my run, so there was no tadpole in the final Prism scene, and Orpheus' transformation was pulled outta the arse for all intents and purposes.
Even then, the number of tadpoles given arbitrary powers for the sake of advancing the plot is getting rather ridiculous (two is already one too many...).
