First, check out the recipe section. I think I saw a recipe for Black Devil there. Try a search. Or, it might have been over on the Vaper's Book. Can't remember for sure. But, I'll bet it is either Capt. Black, Black Djarum or Perique tobacco base with vanilla, caramel and a touch of AP. So, I would do a 20% total flavor recipe with 10% Cpt. Black - 5% Vanilla & 5% Caramel with 1 drop of AP per 5 mls. See if that get close. I'd concentrate on flavor first and then percentages. Vape your recipe in one PV and alternate puffs on a a second PV filled with Black Devil and try and pick out differences. Write down each flavor you taste and research what concentrates might be used.