Recipe for Baracaddus?

Where do you get the recipe and how?

Do all quests in Maldan (southwest of Geat), then go to Arborun, do that quest, and then check the rest of the towns for more quests. Eventually you’ll get a quest that makes you go into the Deucalion Tower to defeat an intruder. Defeat the guy and you should get the barricadus recipe.