Thanks for the tag, I think the biggest issue with your solution (which is creative) is that there's only 1 or 2 total BFs available by the odds. For instance if there are 4000 cards (which there was for the first rebellion set - and this one might be lower because there are less legends printed), then that would mean the odds are only 1 without potions and 2 with all potions available.

There's no way to guarantee enough cards to make the players decide to choose that route.

I like the effort Captain, but the issue is these legendary cards aren't going to be easy to get for anyone. I definitely like the mechanic of choice, I just don't think it applies here in this situation because of the very limited nature of the distribution.