Predicting: monster book

Unless BF is right on a portal, many classes have skills that help them avoid him (Teleport or Recoil, for example). Mounts help everyone avoid BF. Dark Sight also ensures Thieves never have to get hit by him too.

If he's on the portal, you're dead.

I'm pretty sure BF is faster than mounts, and if you get KB'd by a jr wraith or a tree, there's a good chance you're fucked.

Teleport is a gamble made in hell. I wouldn't chance it, and i don't know many mages with the balls to do it either.

Recoil isn't the best avoiding tactic. It's probably the worst actually. You have to aggro it if you use it, and he'll just chase after you probably killing you if you get held up enough.

T.T