Blackmoor has a special magical nature. That's a theme that runs throughout the published material. The Wizards Cabal in particular expands on the idea, explaining the entire territory of the kingdom of Blackmoor is ripe with a magical nature especially attractive to wizards. The dungeons of Castle Blackmoor and the Sages Tower (IIRC) are two especially magically poweful places.

So what does that mean really? There doesn't seem to be any indication (that I know of) that spells cast or magic items made in blackmoor are especially enhanced or successful.

Or are they?

One thing I do note: Superberries. Blackmoor seems to be the only place where these can be grown. Perhaps distilled superberries make magic items easier to make or more powerful or perhaps - like spice in Dune - very small quantities when ingestedenhance the wizards magic ability, inteligence, longevity and so forth. Perhaps all of the above.

Thoughts?

I have always considered the source of magic to have something to do with the magical rock that Blackmoor is built upon. This is mentioned in the DA series IIRC. The crystals used in the D20 line fits quite well with that even if it is never specifically stated. I always assumed that magical herbs and fruits were a result of the magic penetrating the soil from the rock itself.

The magical berries are toned down a bit IMC as I see this as another more humorous element, which doesn't fit as well with my more grim view of the setting.

-Havard