After you have the carpenter build the house for the old lady that unites shamans, go to the northeastern house where the carpenter cooks. Talk to the carpenter and he'll tell you he can cook anything. In the item selection screen use two herbs to make a HelpBL four to make an Elixer. Now to make it infinte, next use either four HelpBL's or two elixers to make a LifePL. So that would mean that you used 8 hervs for a total of 64gp to make one LifePL for a total of 250gp. So sell your LifePL's to make alot of money, buy more herbs and do it again!