HollowCastle has a new place called HollowHalls.In order to HollowHalls you need HollowSoul key then when you go to ArchWraith,next you would see is stairs,go up there then your there.But now you have to be careful because when you walk out there the monster would attack you.To get to the boss you need 3 keys(Red,Green,Blue) from the chest.Btw the place is random to get to the boss.And theres shops for you to get the new items.