Black Magic is home to the ultra-cool "Helix", a hard 12b (maybe a bit of a sandbag at that rating)that actually spirals up into the top of a big cave.One of the most unique routes you will ever do.
There are also many other routes, most of which are 5.12 and harder, including "Simian" (middle 5.13). There are a couple of 11ish routes as well, but not much else to warm up on.
As a destination, I like the Membrane or the Billboard better (more great routes), but this is worth visiting just for a trip up the Helix - fantastic!
Getting There
You can park on the right about half a mile after the visitor center. If you walk up the road a bit, there used to be a pipe that you could use as a bridge across the stream - may still be there.
After crossing the stream , go right on the trail until you come to a big cave. This is it.