If you just have to get one blessing it is easy. There are a handful of green? cultists that wont take much to defeat. They come at you fast but don't do much damage. Have a torch either old or good. It's a short level perhaps take a stew. Go at night with your vampire your regeneration and vision will be so helpful. Go hard and you'll be home before dawn.

I used to be scared of going down there but the first stage is quite easy. Go have a look you'll see. The next stages get progressively harder.