At the casino.
I don't know what the count and situation would have to be for a card counter to get a 10% edge on a hand(I'm sure its possible). I think RS and some others can tell you. We all know card counters don't avrage anything close to 10%.
I don't think one can really get a 10% edge on average hole-carding.
It can come from the machine or from marketing and promotions. You know its 10% by calculating it. I'm not claiming you can walk into a casino and play with a 10% advantage 24/7 365. Obviously, I'm not going to tell you where and how.