Wits end and devourer stuff

So ive been trying devourer vayne again. her w procs in a pattern of 3 hits, 2 hits, 3 hits, and so on. The devourer damage still is kind of weak tho. would wits end make a noticeable difference? and btw because devourer does magic damage, would you need magic pen or armor pen to take down tanks with it. Also, whats the best vayne jg sated build? should i build runaans on her for aoe?

Does anyone know the best regular vayne build? Im using shiv plus firecannon then furor serkers and then usually deaths dance and ie/pd. Im wondering would guinsoos be good on her? and shoul i use the fervor mastery or bloodlust one?

also, why dont i see more sated kog maws?? with that 5.0 attack speed he can hypercarry faster than vayne.