Potion Cask and Kegs are new ways to acquire potions by refilling empty potion flasks that have been added with Update 11.32. Potion casks can only be placed in houses and guildhalls, so you have to go back to your house or guildhall to restock. Each cask may refill 1000 potions of a certain kind. However, potion kegs can be used directly from Your Store Inbox, so you are able to refill your empty potions right away. Each keg may refill 500 potions of a certain kind while weighting the same as 250 potions, which means you save 250 times the potion's weight.