Blood Castle in the early stages, is an easy way to gain lots of Jewel of Blessings which in the later game you will have accumulated so much that you really don't need to farm this but the exp gain is always nice too.

Once you hit lvl 450 you will unlock your barrier which will require upgrade stones that can be farmed here in Blood Castle. Like the Jewel of Blessing by the time you gain 100-200 levels you will have so many that it really doesn't warrant any extra buys on this daily. But the exp gain is always nice.