Black Crawler features lots of roots, some in massive root bundles that will provide a challenge to pass over, especially if they are wet as is usually the case. There are also a couple of rock gardens. This trail is narrow and twisty. Assuming it has rained in the last few days, expect to get dirty. Overall, everything you want in a proper mountain biking trail.
Look for an advanced feature called "The Wall" at about the 0.3-mile mark, or you can take the chicken line around it.
There are a couple of bail points if you are in over your head.