I also bought 5 legendary packs. @azircon suggested that I should buy alchemy packs instead. But like you I have no drawing luck. So considering that with alchemy packs I would probably get no legendary or epic cards...
If someone wants to do the math on what I "should" get using all potions on the 200 Legendary packs, feel free.
My crystal ball says that you will get 20 Black Foil legendaries. But I suck at math...
A low possibility means that it is not zero. That being said I would not bet on either of us getting rich from our purchases...But maybe I am wrong. Maybe all 5 my guaranteed legendary cards will be Black Foil and I will be able to retire continue blogging without worrying about money.
I assume this won't be the case. It would be brilliant if I got a whole set of black :D
I wonder what the actual odds are on that happening.