The Stuff

The stuff is purchased from Honest Jimmy of the Trouble Brewing] minigame on the pirate island of Mos Le'Harmless for 50 Pieces of Eight.

If added to a vat of brewing ingredients just before the hops will give a higher chance of producing a mature batch of whatever ale a player wanted to make.

Put water and barley malt in a brewing vat, then add the stuff, followed by the hops and the yeast.