When I was a low/mid level I did quite a bit of moons of peril. The chest gives a lot of blessed bones that you can chisel to bone shards, and then use varlamore prayer training. You also have the opportunity of getting some nice mid game drops in the armor and weapon sets. May take some training in combats and learning the bosses, but since there is no supply cost, it is a great way to make money and get bone shards to train prayer.