Brutal Strike Advantage.

I understand that you need to forego Reckless Attack's advantage to reap the benefits of the effects/damage, but if the creature is prone or you have some other means to gain advantage, would you still get advantage? Or, is Brutal Strike considered an instance of imposing disadvantage on yourself, so therefore no additional outside sources of advantage could overcome it. I think this interpretation would drastically affect what sort of weapons you chose to bring, specifically thinking of the Topple mastery. Thanks! :]

Brutal Strike very explicitly says you can "forgo any Advantage". That means any advantage on the attack goes away. Any.

Brutal Strike is not considered "an instance of imposing disadvantage on yourself", and it also specifically says you can't use it if the attack has disadvantage.

Thanks, I think that does clear up any ambiguity.