sort of an interesting dichotomy in the meaning of potency. The poison that kills you with the smallest dose is the most potent, but the (hypothetical) drug that cures cancer most effectively is the most potent cancer cure, regardless of dose.
One definition of potency is how little mass it takes to do its thing, whatever that is. Fentanyl is a potent drug, LSD is a potent psychedelic. That resolves the dichotomy.
There’s a second, softer connotation, of how strong it is in light of whatever other limits may exist. Mescaline is less potent in this way, not just because of the larger mass, but because a dose that’s going to blast you into another realm is going to be much harder on you than some other psychedelics.
Ibogaine (haven’t done it) is very potent by this meaning. Very long, intense trips are possible.
all the poisons kill you, one of the poisons is most potent
only one of the cancer cures cures you, but you have to drink a swimming pool of it; thankfully, it's potent enough in that dose to kill the cancer where the other choices only slow it down
