Originally posted by Placidity
If that potion literally does as described, it would've been the ultimate weapon, and as such I think would've been better guarded.
There is a weakness with the potion: if the user does not listen to the "perfect choice" then they can fail. So if the lucky voice prompts the person to go left but they, for whatever strange reason, go right, it fails.
So it is not infallible.
On top of that, it is "banned" from anything that would constitute cheating, it is very rare (apparently, extremely hard to make and it takes 6 months to do so and even slight failures can be very poisonous).
Finally, we really only have one vial of the potion ever seen. Out of all the crap that happened, only one existed. This speaks of its utter rarity. The three kids that took the rest of Potter's FF potion also survived an impossible situation against several death eaters: it should have been sure death for them but not a single spell made contact with them.
Finally, if it can be brewed and sold like nothing, then it speaks volumes about the one of many plot holes created by magical fiction stories.
Originally posted by Placidity
The point about there being a time limit doesn't work out. If I were Dumbles, I would just make it my goal to permanently wipe out all evil forever within minutes, and according to Slugboy, he would succeed.Also, Slughorn is an idiot.
That should work, though. He could easily apparate to every single Death Eaters location and cast the killing curse and do so in less than a minute. That's exactly what the potion should allow him to do.
But herein lies a major CIS moment for Dumbles: he doesn't do that kind of stuff and he steers clear of most dark magic. The only instance I can think of, and it is just speculation (but strongly supported by the movie) is the Fiendfyre he seemingly cast in movie six against the zombies.
You should be able to think of a million and 1 other scenarios, just like that.
There's also the argument that felix felicis was being used by Volde and others during the war but they nulled each other.