The Tosfos Yom Tov in Midos indeed rejects the idea that a magician used magic to build in the Beis ha'Mikdash. However, we should remember that the Beis ha'Parvah is the edifice of Herod, who was not sensitive to religion and might have used magic to promote his building projects. The book Divrei Yissachar Dov suggests that by using the Mikvah in this building they eradicated the effects of the magic.

The Me'iri (Yoma 34) maintains that the magician had forsaken his magic and therefore they named it for him. The Rash, however, says a different explanation: Parvah refers to the hides of the animals from Korbanos which may have been treated in this place. (This is also the meaning of the word in modern Hebrew.)

Yoel Domb