I went through the absolutely painstakingly agonizing process of killing Radahn and Mogh with a +3 weapon at level 12 so I could get hefty pot recipes. They hit like a truck containing 500 toasters though. Very fun.
Add the great jar helm and lighting scorpion charm for even more kaboom.
The funniest thing though? You can easily farm heaps of Hefty Rot Pots without killing a single DLC boss. No need to minmax pot damage or anything, just throw it vaguely into the cooper direction.
I have no idea why base game materials are even limited at this point. Moore should sell infinites of them all by the end of DLC.